March 4, 1904.] 



SCIENCE. 



393 



and this process in the follicle cells of 

 Hydrophilus sp., the common large water- 

 scavenger beetle of our ponds and stream 

 pools, as I have observed it. In the first place, 

 amitosis is not confined to the lowest egg- 

 chamber; unfortunately I can not say from 

 my present preparations how far up the tube, 

 i. e., toward its germinal chamber, amitosis 

 may be found among the follicle cells, but it 

 is found above the last (lowest) chamber. In 

 the second place, there - is no well-definied 

 single nucleolus. So the phenomenon of such 

 a nucleolus surounded by a clear zone and 

 regularly dividing before the nucleus (de- 

 scribed for Qryllus) is wholly wanting in the 

 follicle cells of Hydrophilus. Each nucleus 

 of these cells contains a large number of 

 spherical, strongly staining (chromatin) 

 masses or grains gradating in size from a 

 point up to conspicuously large nucleolus-like 

 balls. The larger of these structures might 

 be looked on as nucleolar masses, if one 

 wanted to use the name nucleolus at all; but 

 if so, from half a dozen to a score of nucleoli 

 would have to be accepted and their only dis- 

 tinction (from the many smaller masses) 

 would be the arbitrary one of size. Fig. 1 

 shows this disposition and relative massing 

 of the staining (chromatin) substance in the 

 nuclei. No sign of chromatin thread (linin 

 or skein) is apparent. There is absolutely no 

 sign of a division of these nucleoli or 

 chromatin balls accompanying the nuclear 

 division. The nuclei simply seem to be senes- 

 cent structures with their chromatin content 

 segregated into many small globular raasses 

 which vary in size, with all intermediate gra- 

 dations from small to large. About each of 

 the larger masses a narrow clear zone is ap- 

 parent. 



Fig. 1 shows also the various stages in the 

 simple division of the nucleus and the great 

 size of the nucleus compared with the cyto- 

 plasm body containing it. In some cases a cell 

 wall appears between the daughter nuclei after 

 division, but in others the cytoplasm does not 

 seem to effect a clean division, both nuclei 

 then lying, it may be said, in one cell. The 

 actual size of the nuclei averages .04 mm. 

 Vernon L. Kjellogg. 



Stanford University, California. 



VARIATIONS IN THE PROTECTIVE VALUE OF THE 



ODORIFEROUS SECRETIONS OF SOME 



HETEROPTERA. 



When on a collecting trip near College Sta- 

 tion, Texas, early in October, I examined the 

 stomach contents of a half-grown toad. In 

 this mass I found two stink-bugs (Euschistus 

 fissilis). This seemed very interesting on 

 account of the great amount of apparently 

 more palatable insects available here; and es- 

 pecially interesting in connection with the 

 fact that the examinations of the contents of 

 152 toads' stomachs since the summer of 1901, 

 made to determine what role the common 

 squash bug played in the toad's diet during a 

 season when these bugs were exceptionally 

 abundant, revealed less than three per cent, 

 hemipterous material. Mr. Kirkland, in Bull. 

 46, Mass. Agric. Coll., p. 16, estimated the 

 percentage of hemipterous and dipterous 

 food, after careful examinations of 149 toads 

 stomachs, below two per cent of the whole. 



There are variations in the protective 

 efficiency of the secretions of some heteroptera, 

 and this may be an important factor in gov- 

 erning the percentage of diet such insects 

 form with some animals. Many experiments 

 with the common black squash bug were made 

 during the surmner of 1901 while at the New 

 Hampshire Experiment Station, and the re- 

 sults there obtained showed that with constant 

 use for a short time the secretions become 

 weaker, and after fifteen minutes are decidedly 

 less effective. Although toads in confinement 

 were witnessed to eat squash bugs, it was only 

 after the secretions were partially exliausted 

 or where the bug was snatched before dis- 

 charging the liquid. The greatest number 

 a hungry toad would eat was three. In no case 

 was this done in the face of a discharge from 

 the secretion glands. 



After twenty-four hours' rest under natural 

 conditions the glands apparently regained 

 maximum strength. This does not apply to 

 hibernating specimens of heteroptera. 



On September 15, 1901, half-grown toads 

 were repeatedly killed from the full effects of 

 the fresh discharges from several specimens of 

 squash bugs. 



