Makch 12, 1909] 



SCIENCE 



433 



A mixture of faeces in water was injected be- 

 tween the valves of uninfected oysters and ttieee 

 oysters were placed in a wire box in the water. 

 After one month these were taken up and exam- 

 ined. Of twenty-six oysters thus treated twenty- 

 two were alive and contained sporocysts of Gas- 

 terostomum immediately outside of the stomach 

 wall. 



This experiment completes the demonstration of 

 the life history as follows: 



1. Adult Gasterostomum in Lepisosteus osseus 

 and in Belone vulgaris. 



2. Sporocysts and cercarise (Bucephalus) in the 

 oyster. 



3. Free immature and encysted Gasterostomum 

 in Menidia and other small fishes which serve aa 

 food for Lepisosteus and Belone. 



The work also indicates the probable identity 

 of Bucephalus polymorphus, found in fresh-water 

 mussels, and Bucephalus haimeanus, found in 

 various marine lamellibranehs. 



Emiryonic Variaiility in Eohinoids : D. H. Ten- 



NENT, Bryn Mawr College. 



Study of variations of plutei of same age, but 

 from eggs of different females. 



Comparison of fed with unfed plutei. 



Study of plutei obtained from eggs of one fe- 

 male which were divided into several portions and 

 each portion fertilized with sperm from a different 

 male. 



Variation in the Tentacles of Eydra viridis: 



Albert M. Reese, West Virginia University. 



These investigations sought to show (1) the 

 variation in the number of tentacles, (2) the 

 relation between the original number of tentacles 

 and the number regenerated after decapitation 

 and (3) the relation between the number of ten- 

 tacles of a bud and the number possessed by the 

 parent. 



Parke states that the number of tentacles varies 

 from four to eleven; and Eand says that in one 

 hundred and fifty Hydras only three had nine 

 tentacles, while about 12 per cent, had eight 

 tentacles. 



In the six hundred Hydras here studied the 

 tentacles varied in number from four to twelve. 

 Only four individuals with the greater number of 

 tentacles were found. About 54 per cent, of the 

 Hydras had eight tentacles, 24 per cent, had seven 

 tentacles, and 15 per cent, had nine tentacles. 

 The other numbers between four and twelve were 

 represented by small percentages. 



Even in different parts of the same twenty-foot 

 aquarium the average number of tentacles varied. 



although the conditions were, apparently, exactly 

 the same. 



As has been noted before, the number of ten- 

 tacles generally increases with the size and the 

 age of the Hydra, though, under unfavorable 

 conditions, the number may decrease with age. 



As has been stated by former workers, the num- 

 ber of tentacles regenerated by a decapitated indi- 

 vidual is nearly always less than the original 

 number possessed by the Hydra. The average 

 number of regenerated tentacles for seven-ten- 

 tacled Hydras was 5.73, for eight-tentacled Hydras 

 it was 6.47. 



Parke states that the number of tentacles on 

 buds varies from four to six, and is always less 

 than the number possessed by the parent. In the 

 Hydras here studied the buds had from six to nine 

 tentacles, and in only 50 per cent, of these cases 

 were there less tentacles upon the bud than upon 

 the parent. In 37.5 per cent, of the budding 

 Hydras examined the number of tentacles of bud 

 and parent was the same, and in the remaining 

 12.5 per cent, of cases the bud had actually more 

 tentacles than the parent. 

 A Report on the First Forty-three Generations 



of an Experiment concerning the Effects of 



Disuse.: F. E. Lutz. 



The fly, Drosophila ampelophila, was bred for 

 more than forty-three generations under condi- 

 tions which prevented the use of the wings. There 

 was no indication of any degeneration either in 

 the absolute or relative size of the wing or in the 

 venation. 

 Darwin's Case of Reversion in Poultry: C. B. 



Davenpokt, Cold Spring Harbor, N. Y. 



The cross between a black Spanish cock and 

 white Silkie hen (an albino) produces black 

 chicks, of which the cocks gain some red in the 

 plumage of those feathers that are red in the 

 jungle fowl. Darwin called this reversion. The 

 second hybrid generation reveals the full story. 

 Typically game-colored males and females appear 

 in this generation. The whole matter is explained 

 on the theory that the Spanish contains the fac- 

 tors: color factor, C; jungle fowl color pattern, J; 

 and extra black coat, N; whereas C and N are 

 absent in the Silkie. In the second hybrid gen- 

 eration theory calls for nine blacks to four whites 

 and three games and this proportion is actually 

 obtained. 



A Substitute for the Theory of Warning Colora- 

 tion: Jacob Reighaed, University of Michigan. 



Many of the coral-reef fishes of the Tortugas 

 region are very conspicuous in their natural en- 



