SEMEN. 



493 



The tlifferencesr in the form and develope- 

 ment of the spermatozoa of lulus fabu- 

 losus are very interesting. The formation 

 of these parts does not confine itself, as in 

 lulus terrestris, to the mere metamorphosis 

 of the nucleus into spermatozoa. Previ- 

 ous to the latter projecting over the ex- 

 ternal surface, the cell membrane gets en- 

 larged on the opposite side (fig, 378. A, 

 B, c) into a corpuscle, which assumes the 



Fig. 378. 



Spermatic cells of lulus fabulosus. 



same shape as the nucleus. The sperma- 

 tozoa in I. fabulosus do not, therefore, con- 

 sist in one short cone, but rather in two 

 such formations (fig. 378. D, E, F), which are 

 turned towards each other with their broad 

 surfaces partially touching. One of these is 

 not unfrequently distinguished from the other 

 by a more considerable size- In a developed 

 state, when the original cell membrane, in 

 which the cone was formerly imbedded, has 

 disappeared, the two parts sometimes separate, 

 each having a perfect resemblance to the 

 spermatozoa of I. terrestris. 



V. Sicbold, to whom we are indebted for the 

 first accurate statement respecting the Chilo- 

 pods*, was not acquainted with the developed 

 forms of these parts in I. fabulosus. He de- 

 scribes as such the stages of developement of 

 the spermatic cells illustrated by us in fig. 378. 

 AtoE, comparing them with the shape of 

 snuff-boxes, in which the lower surface is much 

 thickened, whilst the upper surface contains 

 in the centre a roundish nucleus. 



The spermatozoa of the Chilognatha f are 

 filiform and of a very considerable length and 

 thickness ; e. g. in Geophilus, where they mea- 

 sure \\"' '. Towards one end they gradually 

 become finer, and usually rather undulating 

 or spiral, particularly at the anterior thick 

 part. In Geophilus these fibres are rolled 

 up separately into one ring-like curl ; in 

 Scolopendra, on the other hand, they are 

 straight, and united in small numbers into 

 string-like bundles. Nothing certain is as 

 yet known respecting the developement of 

 these fibres ; but, with V. Sicbold, we think 

 it very probable that they originate from 

 the larger cells (measuring in Geophilus 

 -gL'", in Lithobius ^'" T V") which co "- 

 tain a single, double, or treble nucleus 

 (of .ji^'" --Jo'") w i tn a nucleolus, and 



* Miiller's Ardriv. 1841, S. 13. 



f See Stein. Muller's Archiv. 1842, S. 258. 



which are found in great quantity in the 

 testicles. From analogy we may infer that 

 it is in the nucleus within the vesicle that 

 the fibres are produced. The association of 

 the groups of spermatozoa in fascicles in Li- 

 thobius has, however, no intimate connection 

 with the manner of their production, because 

 the enclosed nuclei never equal in number 

 the united fibres enclosed in one bundle. 

 It is probably the result of a subsequent 

 transition (like the formation of the seminal 

 fibrous strings in the Hexapods). 



Crustacea. Among the Crustacea, to which 

 we now proceed, we likewise meet with, as in 

 the Myriapoda and Arachnida, many vary- 

 ing forms of the seminal elements. The 

 most remarkable are the so-called radiating 

 cells of the Decapods*, small, strangely 

 formed corpuscles of a variable shape (and 

 generally of a size of -5^'" ^b"'), which 

 owe their origin to a metamorphosis of sper- 

 matic cells containing nuclei. By the dif- 

 ferent developement of the nucleus and cell 

 membrane (fig. 379. A, B, c, D), they are 



Fig. 379. 



Radiating cells of Grapsus marmoratus (A), Pa- 

 gurus oculatus (B, c), and Pisa tetraodon (u). 

 (After Kolliker.} 



usually divided into two portions of different 

 shape and size, and are furnished at the bound- 

 ary between the two with delicate and fibrous 

 rays, which vary in number from one to four, 

 but are generally three; but this is effected 

 in such a manner that the rays constantly re- 

 main connected with the division produced 

 from the metamorphosis of the original cell 

 membrane, and never with the nucleus part. 



These radiating cells are produced from 

 the original simple seminal cells in the fol- 

 lowing manner : The nucleus (as in Clu- 

 biona and the lulides) gradually projects 

 further and further towards the outside, 

 thereby metamorphosing itself into a roundish 

 (in Calappa, Hyas, Stenorhynchus, Scyllarus, 

 Astacus fluviatilis, &c.) or spiral (in Cran- 

 gon, Pisa, Galathea, Pagurus) appendix of 

 the cell wall, which frequently enlarges itself 

 considerably, especially in Pagurus, where it 

 reaches -3". In the mean time, the cell 

 membrane has likewise undergone some 

 changes. It either gets flattened more or less 

 (Palacmon, Stenorhynchus, Pica, Calappa), 

 or it lengthens itself into a cylindrical cor- 

 puscle (Galathea, Astacus marinus). It is 

 sometimes the case, however, that it retains 

 its original round form (Ilia, Pilumnus, 

 Pagurus, Astacus fluviatilis). 



At the anterior end of this last corpuscle, 

 where the part containing the nucleus ad- 

 heres to it, the rays now gradually dart forth, 



* Vide the numerous and accurate statements 

 and illustrations of Kolliker. 



