33 



represent a degenerative process induced possibly by abnormali- 

 ties of the fluid environment. It is rather difficult, however, to 

 distinguish between deformities and immature types. The two 

 most common cephalic deformities are Avhat might be called macro 

 and microcephalic forms. In the former, the head is enlarged to a 

 greater or less extent, it is usually defective in staining qualities, 

 and its outline is indistinct, due to degeneration of the covering 

 membrane. This type is seen in Fig. 32. Also the shape of the 

 head is usually abnormal, being either quite rounded, loifg and 

 narrow, or short and very broad. Cells with protoplasmic ap- 

 pendages, though they are more properly an immature type, 

 occasionally give the head a greater volume. Microcephalic sperms 

 vary from those slightly smaller than normal to those in which the 

 head is represented by a slight knob. In some cells, the head is 

 small and round, in others, short and stubby, while another type is 

 normal in outline but diminutive in size. These forms likewise 

 are, as a rule, deficient in staining qualities, and are undoubtedly 

 degeneration forms, occurring either as the result of faulty de- 

 velopment, or degeneration subsequent to their formation. Gary 

 believes they are degeneration types because in the majority of cells 

 the tail is apparently fully formed, and in the normal process of 

 evolution the tail is the last part of the cell to be exhibited. 

 Double headed forms are quite rare, but they nevertheless appear 

 at times. Their significance is difficult to explain. Another very 

 frequent deformity of the head is a marked constriction at the 

 posterior part so that it is the shape of a pear or top as in Fig. 27. 

 In some, the head is otherwise normal in size. Avhile in others it is 

 much elongated, as in Fig. 28, or considerably atrophied. A con- 

 striction at the middle of the head, as in Fig. 29, is not uncommon. 

 Both defects are undoubtedlj'- the result of nuclear deficiency, as 

 the nuclenr part of the head in these cases is much diminished in 

 size, and stains very deeply or not at all. I have seen spermatozoa, 

 the heads of which were like an inverted cone, with a bulging 

 rounded base. Other head.s are even somewhat contorted and bent 

 on themselves, as shown to some extent in Fig. 26. 



Lender caudal deformities, the most frequent form encountered 

 is a thickening of the connecting piece. This may occur as a uni- 

 form thickening, or as a bulging appendage. Rudimentary de- 

 velopment of the tail, the presence of two poorly formed tails, and 

 defective development of the connecting piece occur rather infre- 

 quently. 



All these immature and defective types are. as a rule, motion- 

 less, and of course incapable of producing fertilization. Their 

 presence indicates lowered fertility of the semen. Besides these 

 deformities, there are sperms showing a cur\'ature of the tail at an 

 acute angle just posterior to the neck, — the so-called " wry neck." 

 Their significance is difficult to explain, but they occur frequently 

 in somen fixed and stained by the same routine methods used on 

 samples in which thev are al)sent. They probably are not the re- 

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