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SCIENCE 



[N. S. Vol. XXXVI. No. 932 



tocytes, spermatids and spermatozoa were 

 stained a deep blue. The nuclear network of 

 these cells and the chromosomes and spindle 

 fibers, in all the division stages, were brought 

 out with great sharpness by a somewhat longer 

 application of the dye. 



The separation of the dyad chromosomes in 

 the metaphase figure of a primary spermato- 

 cyte of Anasa was observed. The transforma- 

 tion of anaphase figures of both spermato- 

 gonia and spermatocytes to telophase figures 

 was easily followed. 



When diethylsafraninazodimethylanalin is 

 reduced the color changes from blue to red. 



The possibility of studying nuclear reduc- 

 tions at once became apparent, when it was 

 demonstrated that the stained chromosomes 

 continued to live. By the use of appropriate 

 methods we have been able to follow the rela- 

 tive rate of reduction in the nucleus and 

 cytoplasm. 



In the spermatid the first structure to turn 

 red was found to be the " Nebenkern." Later 

 all parts of the cell show this change. In the 

 cells showing division figures the chromo- 

 somes and spindle fibers began to turn red 

 while the remainder of the cell was still a 

 deep slate blue. The same was found to be 

 true for the nuclear network of resting cells. 

 In the final stage of reduction, all stained 

 cellular structures are red. 



The colloidal structure of the resting and 

 dividing nucleus was studied by means of 

 dissections. The cells, in hanging drops, were 

 dissected with Jena glass needles held in a 

 three-movement pipette-holder. The needles 

 were drawn in many cases to less than one 

 half micron in diameter and the dissections 

 were made under a 2 mm. Zeiss objective and 

 Nos. 6 and 8 compensating oculars. 



Eesting and dividing spermatogonia, sper- 

 matocytes, spermatids and spermatozoa were 

 dissected. Eesting epithelial cells from the 

 skin of the Amblystoma larva were also dis- 

 sected. 



The living cytoplasm of the spermato- 

 gonium, spermatocyte, spermatid and sper- 

 matozoon is extremely glutinous. It fre- 

 quently adheres to the minute glass dissecting 



needle and a large portion of it can be drawn 

 out into strands. This is particularly true of 

 the spermatozoon. Dissections are greatly 

 increased in difficulty, on account of this fact. 

 Dying cells lose their viscidity and may be 

 easily torn to pieces. 



The masses of minute cytoplasmic granules, 

 stained by Janus green, the " Nebenkern " 

 and the middle piece of the spermatozoon, do 

 not readily go into solution when dissected 

 out in Ringer's fluid. Puncturing and tear- 

 ing away parts of the cytoplasm of the sper- 

 matogonium and spermatocyte have no appre- 

 ciable effect on the nucleus. When the 

 cytoplasm or nucleus is punctured, the area 

 immediately surrounding the needle stains a 

 deep blue. If a portion of the nucleus be 

 torn away the remainder does not collapse and 

 gives no evidence whatsoever of loss of sub- 

 stance. The nuclear network can be torn out 

 and is found to be a fairly concentrated, 

 elastic gel, imbedded in a much more dilute 

 viscous gel. Metaphase and telophase spindles 

 neither collapse nor go into solution when 

 freed from cytoplasm. 



Single chromosomes were dissected out of 

 cells in the prophase, metaphase and telophase 

 stages. The chromosome is a fairly concen- 

 trated and somewhat refractive gel. It varies 

 in elasticity in its different phases. A single 

 metaphase chromosome was dissected out with 

 its spindle fiber attached. The spindle fiber 

 is a slightly refractive elastic gel and in the 

 metaphase it seems to be continuous with the 

 chromosome. 



The nuclear network, spireme, spindle and 

 chromosomes are imbedded in a dilute glu- 

 tinous gel that is commonly invisible by the 

 usual microscopical examination. 



In two cases, while attempting to separate 

 the daughter cells of a spermatocyte in telo- 

 phase, a partial rapid reversal of the chemical 

 and morphological changes occurring in cell- 

 division was observed. In two seconds the 

 daughter cells had fused and formed a single 

 cell; the spindle fibers formed an irregular 

 network in which the chromosomes were en- 

 tangled. These observations seem to indicate 

 that cell division is allied to contactility. 



