CYTOPLASMIC STRUCTURES IN THE SEMINAL EPITHELIUM OF THE OPOSSUM. 67 



guinea-pig (1910). The present experience, however, has led me to reconsider this 

 opinion, and I contemplate reinvestigating both the rat and the guinea-pig at an 

 early date. 



The number of the chondriosomes eliminated varies, but is usually very small 

 (figures 15a, 156, 19, 20, and 21). On the other hand, the number of chondriosomes 

 on the middle piece is fairly constant, as will be shown later. The quantity elimi- 

 nated is consequently a function of the quantity held by the spermatid, all the 

 chondriosomes (no matter how numerous) that do not find a place on the middle 

 piece being eliminated. To the significance of this elimination Jordan seems to 

 attach much importance: 



"The loss of a considerable amount of mitochondrial substance in the cast-off portion 

 of the spermatid * * during the process of metamorphosis, militates against the 



interpretation of mitochondrial continuity and a hereditary role of this substance (page 



70)." 1 



Setting aside the fact that the amount eliminated is not considerable, I fail 

 entirely, as stated before (1912, page 624), to see what theoretical importance it can 

 have. 



To return to the chondriosomes surrounding the axial filament, let us note their 

 further evolution in Regaud's preparations. While the superfluous chondriosomes 

 are migrating toward the anterior part of the spermatid to be later eliminated, the 

 others become gradually distributed with considerable regularity (figs. 19, 20, 21; 

 also fig. 15a). When the elimination is completed (fig. 22) all the little rods are 

 arranged obliquely in relation to the axial filament and at the same time are laid 

 out in regular longitudinal rows suggesting a fir-apple or an ear of corn. The same 

 regularity appears also in preparations after Benda, although, as already men- 

 tioned, instead of rods we find in these rather large granules (fig. 15a). The num- 

 ber of elements in each longitudinal row can be estimated up to seven or eight, and 

 in cross-section, seven (fig. 156); the total number of chondriosomes would con- 

 sequently be 49 to 56. At the anterior part of the middle piece preparations after 

 Regaud show invariably some irregularity in the disposition of the chondriosomes, 

 inasmuch as some of them (usually two) are disposed almost perpendicular to the 

 others (figs. 21 and 22). These, I assume, are going to form the first winding of the 

 spiral. 



FOURTH PERIOD. 



From the description given above it results that, at the time of the elimination 

 of the residual body, no spiral has been formed. Its formation belongs entirely to 

 the fourth period; in other words, it takes place in the spermatozoon eliminated in 

 the lumen of the seminiferous tubule. First, the rods dispose themselves perpen- 

 dicular to the axial filament and appear somewhat thinner; the two anterior ones 

 seem to have fused together into one curved filament (fig. 23). Then, by confluence 

 of the rods the spiral is formed. In material fixed in Benda's fluid it is perfect in 

 its regularity (fig. 16); after Regaud's fixation it is somewhat irregular (fig. 24). 



'A similar opinion was again expressed by Jordan in 1914 (p. 167). 



