rEBKUAET 19, 1915] 



SCIENCE 



291 



lated and studied by means of microdissection 

 and vital staining in a hanging drop of the 

 insect body fluid in Barber's moist chamber. 



The cytoplasm exhibits an extreme varia- 

 bility in its consistency. On tearing it may 

 go into solution, setting free the nucleus and 

 the cytoplasmic granules. Often the cyto- 

 plasm goes into solution with a rapidity 

 suggestive of an explosion. A slight tear- 

 ing of the surface is followed by a moment 

 of apparent inactivity. Then comes a slight 

 convulsive movement and the torn surface 

 opens up, a swelling appearing especially at 

 this place. Within a few seconds nothing re- 

 mains but the nucleus and the mitochondria 

 in the form of granules or a network. The 

 nucleus in its turn swells and goes into solu- 

 tion. The mitochondria persist for a much 

 longer time. Individuals are also met with 

 whose cells retain their shape, the torn region 

 being gradually obliterated by a closing in 

 of the surrounding cytoplasm. 



It is significant that all the cells of a given 

 individual are constantly uniform in their 

 behavior. 



In an attempt to ascertain the cause for this 

 variability in the consistency of the proto- 

 plasm a series of experiments has been 

 planned, one of which is the investigation of 

 the germ cells of food and water starved indi- 

 viduals. Cockroaches starved for three weeks 

 in a dry heated room were found uniformly to 

 possess germ cells remarkable for their tough- 

 ness and resistance to mechanical injury. 



" Physiological " salt solutions in various 

 dilutions were all found to produce a swelling 

 effect on the cell. The first evidence of this in 

 isolated cells is the assumption of a spherical 

 shape. The addition of a trace of egg albumin 

 counteracts the swelling to a slight extent. 

 As swelling proceeds the viscosity of the 

 protoplasm at first increases, agglutination 

 phenomena becoming very marked. Later the 

 viscosity is lost, possibly due to the increased 

 imbibition of water. 



When observed in body fluid, the cells tend 

 to keep their irregular shapes. Spermato- 

 cytes exhibit slow amceboid movements. Iso- 

 lated cells, however, soon become spherical. 



They also become spherical and swell on in- 

 jury as when they are punctured with a needle. 



The mitochondria in the primary sperma- 

 tocyte of Bisosteira form a voluminous gran- 

 ular network surrounding the nucleus, plainly 

 visible in the fresh unstained cell. The deli- 

 cate tracery of the mitochondrial structures in 

 this, and in subsequent, stages is shown beauti- 

 fully with Janus green, beside which similar 

 structures seen in fixed material appear crude 

 and in many respects erroneous. If the Janus 

 green stain be heavy, its coagulative effect is 

 apparent in the increase and clumping to- 

 gether of the granules. If the cell be torn, 

 the cytoplasm goes into solution and the stain 

 very soon fades out, the granules swell and 

 coalesce, forming irregular lumpy masses 

 which persist for a long time. 



During metaphase the mitochondrial net- 

 work is pulled out into a spindle-shaped struc- 

 ture investing the viscous kinoplasmic mate- 

 rial. Tearing of the cytoplasm causes a loss in 

 the bipolar arrangement of the cell structures, 

 the mitochondrial strands wrinkle and the 

 whole spindle becomes distorted. The chrom- 

 osomes scatter. Within a few minutes the 

 relatively dense kinoplasmic mass goes into 

 solution leaving the mitochondrial network 

 with the chromosomes irregularly dispersed 

 inside. In one such case two spermatozoa 

 corkscrewed their way between the meshes of 

 the mitochondrial spindle. Whenever their 

 tails touched the viscous material of the 

 meshes violent lashings were necessary to set 

 themselves free. One struck its head against 

 a mesh and was held prisoner for several 

 minutes until the viscosity of the material 

 was decreased during the dissolution process. 

 The other spermatozoon hit a chromosome 

 which stuck to its tail and the spermatozoon 

 twirled away dragging off the chromosome. 



During anaphase and telophase the gran- 

 ules and strands of the mitochondrial network 

 are lengthened into delicate filamentous 

 threads lying between the two groups of 

 chromosomes. These are the interzonal fila- 

 ments or the spindle-rest described in fixed 

 material. As constriction between the daugh- 

 ter cells progresses, the tension of the fila- 



