WILCOX : SPERMATOGENESIS. 9 



scattered about the cell irregularly after the nuclear membrane degen- 

 erates. Or the fragments may fuse into one mass, which subsequently 

 breaks up. But quite often in Cicada the metamorphoses of these 

 nuclei are rather regular, presenting stages very similar to those which 

 the normal spermatid undergoes. I am not aware that any one hitherto 

 has suggested that the giant spermatozoa arise directly from sperma- 

 togonia, and a priori it seems, I admit, quite improbable ; yet my Cicada 

 preparations point very strongly to this conclusion. 



CALOPTENUS FEMUR-RUBRUM. 



The testes of Calopteuus consist of tubular follicles, which lie closely 

 packed together, parallel to one another. They are of nearly the same size 

 throughout their length, being slightly larger near the blind end of the 

 tubule, and tapering thence into the collecting duct, which opens into 

 the vas deferens. In my Calopteuus material, taken in August and 

 September, the spermatogonia were confined to a single compartment at 

 the blind end of the tubule. After the spermatogonia the other stages 

 follow in regular succession, a considerable part of the follicle being 

 occupied by the prophases of the first division of the spermatocytes. 

 Then follow regions in which the two successive cell divisions are taking 

 place, then the spermatid metamorphosis, and finally the nearly mature 

 spermatozoa, which with the degenerating cells entirely fill the lumen 

 of the tubule. Figure 108 (Plate III.) represents a longitudinal section 

 of a follicle, in which spermatogonia are shown at a, prophases of the 

 first spermatocyte division at b, the first division at c, spermatids at d, 

 immature spermatozoa ate, and degenerating cells at/. The stages of 

 spermatogonia preparatory to division are seen in Plate III. Figs. 105- 

 107, and Plate IV. Figs. 164-168. Spermatogonium divisions are 

 shown in Plate III. Figs. 119-121, 124, 131, 138, and Plate IV. Figs. 

 169-171, and a tripolar division at Plate IV. Fig. 189. I could not 

 determine how many divisions the spermatogonia undergo. The chro- 

 mosomes in the prophases are twelve in number, twenty-four at the 

 equator of the spindle, during rnetakinesis. The individual chromosomes 

 are rod-shaped or often elongate spindle-shaped. In rnetakinesis they 

 show ordinarily the well known V-shaped figures, and are connected with 

 each other in pairs by means of limn fibres. The centrosomes are usually 

 apparent (Plate III. Figs. 105, 132). Figure 105 shows the centrosome 

 surrounded by a clear protoplasmic area. In most cases a nucleolus is to 

 be seen during the prophases. In Figure 106 there is in the nucleus a 

 body (nucleolus'?) which seems to have recently divided. 



