578 



SCIENCE. 



[Vol.. II., No. .OS. 



one red Pulmoiiaria. and one Nepeta. Coming, now, 

 to a place where the ground-ivy prevailed, she visited 

 sixty-one Nepeta flowers, then five red Pulmonaria 

 flowers, after which she returned to her nest. Earlier 

 observation has also shown that this bee is not con- 

 stant in its visits to a given species. The visits of 

 the second individual and of one or two other in- 

 sects, watched but a short time, to the blue flowers, 

 is attributed to their lack of experience on this species ; 

 while the promiscuous visits of others are believed to 

 be due to a noticeable confusion which was mani- 

 fested after one or two unsuccessful visits had been 

 made to flowers drained by earlier comers. From his 

 observations, the writer concludes that the blue color 

 of the older flowers, like the final color of those of 

 Eibes aureum and Lantana, is of twofold advantage 

 to the plant, — on the one hand increasing the con- 

 spicuousness of the flower-cluster, while, on the other 

 band, it indicates to the more acute of the visiting 

 insects the flowers to which their attentions should 

 be confined for their own good and that of the plant. 



— (JTosmo.?, 1SS3, 214.) w. T. [319 

 Insects versus fertilization. — In some notes on 



Thripidae, Mr. Osborn discusses the food-habits of 

 these minute insects, believing, from the structure 

 and position of their mouth-parts, and such observa- 

 tions as he has been able to make, that the major 

 part of the group are vegetable feeders, the few spe- 

 cies considered by Walsh and Kiley as insectivorous 

 differing in this respect from most of their congeners. 

 Even these are thought to possibly seek the honey- 

 dew of aphides, etc., rather than to destroy them. 



Of young apple-blossoms frequented by them, 

 "eighty per cent were injured by punctures upon the 

 styles and other parts, but particvilarly the styles; 

 and all the evidence pointed to the thrips as the 

 cause of injury," though they were never seen to 

 actually puncture the tissue. — (Canad. entom., Aug.) 

 w. T. [320 



ZOOLOGY. 



Origin of iudividiiality in the higher animals. 



— H. Fol ha< published a very interesting note, in 

 which he studies, not the historical or phylogenetic, 

 hut the physiological, origin of the individual. The 

 questions proposed are. At what moment in the onto- 

 geny is the individuality created and limited ? What 

 factors determine the development of one, two, or 

 several embryos from a single vitellus ? The cases 

 of double monsters by union of two distinct eggs, 

 and polymerism, being phenomena of a different 

 order, do not come into considei'ation here. 



Fol's new researches were made principally on 

 the sea-urchin, Stroiigylocentrotus lividus, which is 

 strictly individualized at all stages of lis existence. 

 He had previously reached the conclusion that nor- 

 mal fecundation demands only one spermatozoon for 

 each egg. Selenka thinks that two or three do not 

 involve the sequel of an irregular development. 

 Fol has verified both points, and finds that normal 

 fecundation may be effected by either one or two 

 spermatozoa uniting with the egg-nucleus. Three 

 seem to produce abnormalities. The spermatozoon, 

 then, does not act as an individuality: it represents 



only a certain dose of nuclear substance; and the 

 dose may he either single or double. Immature or 

 injured eggs admit several spermatozoa. Yery in- 

 geniously Fol has produced such a condition tempo- 

 rarily by immersing the mature ova for a moment 

 in water saturated with carbonic acid, then trans- 

 ferring them to well-aerated water, and impregnat- 

 ing. The half-asphixiated eggs admit each three 

 or four spermatozoa, which unite with the female 

 pronucleus, after which follows an abnormally long 

 period of repose. When segmentation begins, there 

 appears a complex caryolytic figure, with three or 

 four poles instead of two, a triaster or tetrastcr, or 

 two parallel amphiasters, separate or united. The 

 number of segmentation-spheres formed is at least 

 double the normal. The larvae have irregular forms, 

 and often two or three gastrular cavities. 



If the eggs are more completely under the influ- 

 ence of the carbonic acid, from five to teix sperma- 

 tozoa may gain entrance. The earliest comers unite 

 with the female pronucleus: the later ones remain in 

 the peripliery. The nucleus forms a tetraster or dou- 

 ble amphiaster; and the peripheral male pronuclei 

 form each an amphiaster, which usually join end to 

 end, forming a rosary of asters and spindles. Each 

 of these amphiasters seems to be a centre of develop- 

 ment, for the surviving larvae are polygastric. 



These facts lead to the conclusion that neither the 

 egg, nor the female pronucleus, nor the spermato- 

 zoon, suflSces, taken separately, to determine the indi- 

 viduality. The dose of nuclear substance resulting 

 in the formation of an embryo may vary within 

 considerable limits; and the number of amphiasters 

 at the first cleavage is the first criterion which 

 decides the number of individuals. Fol then con- 

 siders the first amphiaster of segmentation as the 

 first fact of individuality. [Fol does not appear to 

 have demonstrated a strict correspondence between 

 the number of amphiasters and of individuals. His 

 view raises the question whether there is a funda- 

 mental difference between the bipolar (amphiasters) 

 and multipolar asters in cell-division.] — {Coniples 

 rendus acaO. Paris, Aug. 13, 1SS3. ) c. s. m. . 1 321 



VERTEBRATES. 

 Eirds, 

 The ■white of birds' eggs. — Tarchanoff has dis- 

 covered that the white of the eggs of those birds 

 whose young are born unfeathered differs from or- 

 dinary albumen, its most striking peculiarity being 

 that it remains transparent after coagulation by heat. 

 He designates it as ' tata-eiweiss.' It [differs from 

 ordinary white of egg in many respects. When co- 

 agulated it is fluorescent. It has less polarizing 

 power, and contains more \yater, than the white of 

 hens' eggs. It gives no precipitate when abundantly 

 diluted with water. It is at first strongly alkaline, 

 but loses that reaction as the yolk develops. It is 

 rapidly digested. It can be redissolved in water 

 after drying at 40° C. It can be changed into what 

 appears to be identical with ordinary albumen, a, by 

 the addition of a few drops of concentrated solutions 

 of neutral salts of alkaline b.ases, or, h, of coucen- 



