April 4, 1902.] 



SCIENCE. 



523 



bers frequently fused into a common mass. 

 The nuclear conditions in these large 

 fusion-masses offer an interesting object 

 for study. 



At the end of a period slightly longer 

 than in the normal development the ecto- 

 plasm became vacuolated and ciliated. By 

 the action of the cilia the eggs often rotated 

 rapidly in the water. In the largest fusion- 

 masses cilia appeared only on restricted 

 areas. 



Certain of the phenomena of ontogeny 

 are thus shown to be independent of cell- 

 division. It may be expected that further 

 study of the material and careful analysis 

 of the results will aid in the understanding 

 of the mechanism of the earliest phenomena 

 of development. 



In conclusion, acknowledgment was 

 made to the aid received from the subse- 

 quent work of A. D. Mead and Jacques 

 Loeb. 



The Rate of Growth in Marine Inverte- 

 brata: A. D. Mead. 



Ingestion and Digestion in Hydra: Elliot 



R. Downing. 



Many observers have noted that the 

 mouth of hydra is capable of great expan- 

 sion, so that it can swallow comparatively 

 large animals. The mouth is not a simple 

 circular orifice; a cleft runs out from the 

 center of the peristome toward each arm, 

 so that it is divided into as many lobes as 

 there are arms, the lobes alternating with 

 the arms. The circumference of the 

 expanded mouth is therefore as great as 

 the contour of this radiate figure. These 

 lobes at the margin of the peristome are 

 double the thickness of the ordinary body 

 wall on account of the greatly increased 

 length of their endoderm cell. They 

 become thinner toward the mouth and also 

 where they merge into the body wall below 

 the level of the tentacles. They are trav- 



ersed by longitudinal muscle fibers con- 

 tinued from the body wall. 



Ingestion is followed promptly by diges- 

 tive processes. Within a few minutes after 

 ingestion certain gland cells become appar- 

 ent in the endoderm. These cells contain 

 a nucleus which rapidly enlarges and 

 becomes granular. As noted in the diges- 

 tive processes of higher animals, these cells 

 are probably forming enzymes. They rap- 

 idly decrease and finally disappear as the 

 ferment is discharged into the body cavity. 

 These gland cells stain best with gentian 

 violet after osniic-Merkel. 



The digestive process is rapid. Last 

 June I observed a good-sized hydra ingest 

 a young carp 8 mm. long. Seven hours 

 later, as determined by sectioning, no trace 

 of this remained in the digestive cavity. 

 The digested material is absorbed by the 

 endoderm cells, which after a meal are 

 gorged Avith food spheres; much of this 

 material, especially the oil, is passed on to 

 the ectoderm cells, where it is stored. The 

 fatty substance accumulated at the periph- 

 ery of these cells forms a layer of droplets 

 which may be stained an intense black by 

 osmie acid. It is these fat droplets which 

 during life give to hydra its brown color. 



The History of the Eye of the Blind Fish 

 Amhlyopsis: Carl H. Eigbnmann. 

 The history of the eye of Amhlyopsis 



may be divided into four periods : 



(a) The first extends from the appear- 

 ance of the eye till the embryo is 4.5 mm. 

 long. This period is characterized by a 

 normal palingenie development, except that 

 cell division is retarded and there is very 

 little growth. 



(b) The second period extends till the 

 fish is 10 mm. long. It is characterized by 

 the direct development of the eye from the 

 normal embryonic stage reached in the first 

 period to the highest stage reached by the 

 Amblyopsis eye. 



