HUMAN SPERMATOGENESIS: A STUDY OF INHERITANCE. 13 



II. Spermiogenesis. 



4 



A. OBSERVATIONS. 



1. Nuclear Changes and Formation of the Cuff. 



Figs. 56-58, PI. Ill, exhibit the early rounded nuclei of spermatids, in which 

 there are to be seen irregular masses attached to the reticulum. These were 

 drawn from iron-haematoxylin stains, by which plasmosomes cannot be sa is- 

 factorily distinguished. But with the use of the Ehrlich-Biondi stain a single 

 red-staining plasmosome may generally be distinguished near the center of the 

 nucleus, and sometimes one or more densely green bodies, which lie usually 



against the nuclear membrane; the latter may be either allosomes or karyosomes, 



I have not attempted to decide which 



Then follows an elongation of the nucleus (figs. 59-61) in the direction of the 

 centrosomes. This is immediately followed by a retraction of the nuclear wall 

 near the centrosome pole, whereby at that point the nucleus becomes concave, 

 and just at that concavity appears a drop of fluid in the cytoplasm. This drop 

 {Co, figs. 62, 63) is the first appearance of the substance of the cuff; it has bern 

 represented on this and succeeding figures by dark shading simply to make the 

 drawing more distinct, but in the preparation it appears lighter than the cyto- 

 plasm. Its appearance simultaneously with the shrinkage of the nucleus, which 

 from now on, decreasing in volume becomes gradually more dense, proves that 

 it is discharged karyolymph. The nuclear membrane always seems to be intact 

 opposite the drop, and the drop at first is not sharply bounded on its outer surface. 

 Consequently there can be no doubt of its extra-nuclear position. Shrinkage of 

 the nucleus and enlargement of this cuff substance go hand in hand showing that 

 the two are dependent phenomena. 



The nucleus shrinks most markedly in its distal position, which frequently 

 exhibits irregular prolongations (figs. 66, 71), and this portion early becomes 

 dense and loses all nuclear sap as is clearly observable in the succession of stages 

 on Plate III. Most frequently this posterior portion of the nucleus becomes a 

 pointed cone demarcated from the anterior, more rounded portion by a slightly 

 projecting annular girdle that is to be seen in most of the figures. But the pos- 

 terior portion offers a great variety of forms during the spermiogenesis, due in 

 part to the angle from which the nucleus is viewed, in part, also to variation in 

 method of condensation. Great lengthening of the posterior portion is quite 

 frequent, such as shown in figs. 70, 73, 74, 75, 83, 85. The process of discharge of 

 karyolymph from the nucleus continues until the posterior portion of the latter 

 becomes quite dense, while the anterior portion never loses all of its karyolymph 

 but always retains one or more droplets of it. Thus though the two regions of 

 the nucleus are readily distinguishable they differ mainly in that the posterior 

 region discharges all its karyolymph and so undergoes the greater shrinkage. 



4 Guyer's fig. 18 showing two spermatids " one without chromatin nucleoli, the other with two " 

 was drawn after iron-hsematoxyline staining, and therefore does not prove these bodies to be allosomes. 



