26 



The remarks just quoted show that Dr. Nansen had not 

 acquainted himself with the generally accepted facts concerning sper- 

 matozoa in general. If he had done so he would have known that in 

 all cases hitherto described the head of a spermatozoon consists almost 

 entirely of a nuclear body (chromatin) and the tail exclusively of extra- 

 nuclear protoplasm. It is certainly not true that nuclear matter can 

 be recognised in the tail of the spermatozoon in Myxii/c. and if it were 

 true it would require to be proved by satisfactory evidence. 



An examination of Dr. Nan s en's figures shows that he had not 

 sufficiently mastered the histological methods which he employed. He 

 represents the elements as stained with saffranin, but in most cases 

 the staining is diffuse and not selective or differential. I conclude from 

 the figures that he neglected to wash out the stain from his prepara- 

 tions in the proper manner and to the right degree. In his figures of 

 the three kinds of elements I have mentioned, the extra-nuclear proto- 

 plasm is stained almost as much as the supposed nuclei. The nuclei 

 are in many of the figures, especially in those of the spindle-shaped 

 cells and the ripe spermatozoa, indefinite and without characteristic 

 structure. The nuclear part of the head in the spermatozoa is almost 

 indistinguishable from the extra-nuclear portion. In the figures of the 

 spindle-shaped cells what are indicated as nuclei are not nuclei at all. 

 I procured plenty of material in Norway, and have made many pre- 

 parations stained with saffranin, and in all the preparations I find a 

 definite, deeply stained, small nucleus in the larger spindle-shaped 

 cells, which is not represented in Dr. Nans en's figures; while the 

 central elongated deeply stained portion in Dr. Nansen's figures is 

 seen to consist merely of the central protoplasmic strands of the cell 

 which, in consequence of the drawing-out of the poles, run in the 

 direction of the axis of the spindle. 



Both in the fresh preparations examined and drawn in Norway, 

 and in sections made since my return, I have seen again and again 

 spermatozoa continuous by their tails with the poles of the spindle- 

 shaped cells. I am inclined to think that spermatozoa are given off 

 from the spindle-shaped cells in succession, each head being formed 

 by a fragment of the nucleus, until no more nucleus is left, when a 

 small spindle of non-nucleated protoplasm is left behind as a useless 

 remnant. 



It seems to me therefore certain that each spermatoblast gives rise 

 in Myxine as in other animals to a number of spermatozoa, and that 

 the spermatozoa separate from the spermatoblast not tail first as in 

 other animals, but head first. I hope soon to publish full details of my 



