370 



SCIENCE. 



[N. S. Vol. IX. No. 219. 



ultimately the same individuals become 

 rhombogens and thenceforth produce only 

 infusoriform young. Certain Dicyemids 

 were found to contain both vermiform and 

 infusoriform young. E. Van Beneden's view, 

 that the infusoriform is the maleDicyemid, 

 was confirmed by a study of its structure 

 and a comparison of this form with the male 

 Orthonectid (Rhopalura). From the fact 

 that deeply staining bodies resembling the 

 granules of the urn of the infusoriform, and 

 probably for that reason spermatozoa were 

 found among the germ-cells of the infusori- 

 gen, it was inferred that the infusoriform 

 young may arise from fertilized ova, and 

 that the infusorigen may be an adaptation 

 for accumulating the germ-cells around a 

 central cell to which the spermatozoa are 

 also attracted, possibly by chemotaxis. It 

 was regarded as probable that both the male 

 (infusoriform) and female Dieyemid migrate 

 into the kidneys of the young Octopus and 

 there form colonies of nematogenic females 

 before males are produced. 



Notes on the Blind Fishes. G. H. Eigen- 



MANN. 



1 . Theke is a color pattern common to all 

 the species of the Amblyopsidte. This pat- 

 tern is due to the arrangement of the chro- 

 matophores along the connective tissue 

 septa separating successive muscle seg- 

 ments. The result is a series of longitu- 

 dinal stripes where the septa are bent on 

 the surface and a series of zigzag cross 

 streaks. This pattern is best marked in 

 Chologaster agassieii, in which but little 

 color is present. It is somewhat obscure 

 in Chologaster cornutus on account of the 

 great development of pigment. It remains 

 only as an arrangement of chromatophores 

 in the blind members of the family where 

 color is no longer present in sufficient quan- 

 tity to be evident to the naked eye. 



2. Chologaster agassizii, which has so far 

 been known from the type only, was secured 



through a grant from the Elizabeth Thomp- 

 son Science fund. It is a species with well 

 developed eyes living permanently in caves. 

 Its eye is notably smaller than that of the 

 other species of Chologaster which live in 

 open waters. The retina is very much like 

 that of C. papilliferus, with thinner pigment 

 layer. The eyes of the species of Cholo- 

 gaster show the following measurements : 

 C papilliferus, 32 mm. long. Vertical diameter, 



.832 mm. Longitudinal, .880 mm. 

 C. agassizii, 39 mm. long. Vertical diameter, .720 



mm.' Longitudinal, .800. 

 0. cornutus, 32 mm. long. Vertical diameter, 



.960 mm. Longitudinal, 1.120. 

 Thickness of the retina of 

 C. papilliferus, 29-34 mm. long, .122 mm., 55 mm. 



long, .162 mm. 

 C. agassizii, 38 mm. long, .107 mm., 62 mm. long, 



.130 mm. 

 C cornutus 27 mm. long, .73 mm., 43 mm. long, 

 .83 mm. 



3. The blind fish from Missouri is of dif- 

 ferent origin from the blind fishes east of 

 the Mississippi. The details of this part of 

 the paper have appeared in Science. 



Megeneration and Regulation in Hydra viridis. 



Herbert W. Rand. 



In a series of regenei'ation experiments 

 upon Hydra viridis it was found that the 

 polyps regenerate, on the average, fewer 

 tentacles than are originally possessed. 

 The more tentacles before regeneration the 

 greater is the mean number after regenera- 

 tion. Eight-tentacled Hydras showed the 

 greatest reduction in the number of tenta- 

 cles. Six-tentacled Hydras showed no re- 

 duction. 



The average deviation from the mean 

 was practically the same before and after 

 regeneration. The average deviation from 

 the mean after regeneration, and also the 

 average deviation from the original num- 

 ber, was greater in the eight-tentacled 

 groups and least in the six-tentacled. 



The mean number of tentacles regener- 

 ated by whole six-tentacled Hydras was 



