Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29465/505/
SEMEN. 495 
it lengthwise, until they perforate the exter¬ 
nal enclosure at one end, and now gradu- 
Fig. 383. 
Developement of the Spermatozoa in Mysis. 
( After Frey and Leuckart.') 
ally project outwards (b, c). The number 
of the fibres thus formed is generally limited 
to one. We have, however, seen cylinders 
which contained three or four (c). 
The formation of the spermatozoa in the 
radiating cells of the other Decapods, in our 
opinion, takes place in the same manner. 
Judging from analogy with Mysis, at least, 
we cannot share the conjecture of Kolliker, 
that the rays would simply drop off and 
change into spermatozoa. It appears to us 
much more probable that they are pro¬ 
duced, as in Mysis, in the interior of the 
cell, and that the growing out of rays is 
merely a secondary event, caused by the 
circumstance that the spermatozoa formed 
in the interior urge the external membrane 
forward with one end, and ultimately pene¬ 
trate through it. The projection of the semi¬ 
nal fibres, in Mysis, from the cylinder, has 
indeed much the appearance of their growing 
out into a thin and long appendix. 
Thus much respecting the remarkable semi¬ 
nal corpuscles of the Decapods. We must 
still, however, mention the circumstance that 
the radiating cells in the lower division of the 
testicles, or in the vas deferens, are generally 
still enclosed by peculiar spermatophora, 
like capsules, which possess a round or oval 
shape, and are often attached, by means of a 
solid peduncle, in great numbers, one behind 
another, to one common round or flat jelly- 
like mass. 
The spermatozoa in the other orders of the 
Malacostraca, the Amphipoda, and Isopoda, 
are uniformly filiform. Their developement 
takes place in the usual way, without the 
intervention of radiated cells. 
The length of the spermatozoa, in most 
cases, is very considerable : in Hvperia medu- 
sarum f", in Iphimedia obesa in Jdotea 
tricuspidata ff", in Gammarus Pulex 
The thickness, on the other hand, is compa¬ 
ratively only slight, being most considerable 
in the centre, whence the fibre gets gradu¬ 
ally thinner towards both ends. Kolliker 
describes, in the spermatozoa of Iphimedia 
and Hyperia, a thicker cylindrical and oval 
end, like a peculiar corpuscle. V. Siebold 
does the same with regard to Asellus aqua- 
ticus. We believe, however, that such an 
Fig. 384. 
Spermatozoa of Gammarus Pulex. 
appendix {fig. 384.), or this so-called corpus¬ 
cle, is merely the adhering remainder of the 
mother cell, from which the spermatozoa pro¬ 
ject. Of this we have convinced ourselves 
in Gammarus Pulex. It is certainly difficult 
to distinguish the seminal fibre in the interior 
of it, but it appears to us that our observa¬ 
tions are sufficient to render doubtful the 
interpretation of Kolliker, when we consider 
that this corpuscle occupies so variable a 
position with respect to the fibre, now lying in 
the same line with it, and at other times 
passing into it at a larger or smaller angle, 
quite in the same manner that we have ob¬ 
served in the cylinder of the seminal corpuscle 
of Mysis. 
The variable shape of the body, which 
Kolliker describes in Hyperia, and which we 
have also found, although less remarkably so, 
in Gammarus Pulex, might also speak in 
favour of our opinion. 
The formation of the seminal fibres in the 
Oniscidœ, according to our observation, also 
takes place in the interior of transparent 
cells*, which reach and fill up by 
their number the sacs of the testicles. As soon 
as the developement of the spermatozoa has 
commenced in the interior, the cells grow to the 
extent of and in so doing assume an oval 
shape. The contents then usually become 
rather granular, but the windings of the 
transparent spermatozoa can nevertheless be 
recognised now and then. The vesicular 
seminal elements of Gammarus Pulex, on the 
* The large egg-shaped corpuscles (of J/ O which 
possess, besides nucleus and nucleolus, dark gra¬ 
nular contents, and which form the epithelium 
of the vas deferens, but which are wanting in the 
genuine seminal tubes, should not be confounded 
with these seminal cells. Similar cells, only smaller 
(ofabout2j^'"), are likewise found in the spiders; 
but, although they occur in the seminal cor¬ 
puscles of the palpi, they are not in any way con¬ 
nected with the production of the spermatozoa.
        

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