270 



SCIENCE. 



[N. S. Vol. XXI. Xo. 529. 



minute cell with a few nuclei. There is no 

 definite body form. Development follows 

 the neosporidian type; i. c, nuclear multi- 

 plication and spore formation proceed pari 

 passu with vegetative growth. There are 

 two developmental cycles, resulting in the 

 production of 'round bodies' and of spores. 

 The 'round bodies' are 1.5 to 2 microns in 

 diameter and contain a very irregularly 

 shaped nucleus. The spores are ellipsoidal, 

 5 microns long and contain a round, oval 

 or dumb-bell shaped nucleus. The parasite 

 occurs in enormous numbers, but does not 

 appear to exert a deleterious influence on 

 the host. 



Descriptions of a New Genus of Tanaidce 

 and a New Species of Tanais, 'both from 

 Monterey Bay, California: Harriet 

 Richardson, Smithsonian Institution. 



Isopods from the Alaska Salmon Investiga- 

 tion: Harriet Richardson, Smithsonian 

 Institution. 



An Unnoticed Organ of the Sand-dollar, 

 Echinarachnixis parma: Emily Ray 

 Gregory, Wells College. 

 A study of the morphology of the sand- 

 dollar has shown the presence of a blind- 

 ending diverticulum of the intestine which 

 passes around the body-cavity, giving off 

 branches on the outer side. In the young 

 animal it is frequently distended with 

 sand, but ' generally only a few grains of 

 sand are found in it in the adult. The 

 organ appears to be of most importance to 

 the young animal, but whether its chief 

 value is in removing sand from the in- 

 testine at this time or in carrying it to the 

 different parts of the body cavity, has not 

 been determined. 



Physiological and Morphological Changes 

 during 800 Generations of Oxytricha 

 fallax: Lorande Loss Woodruff, Co- 

 lumbia University. 



A culture of Oxytricha fallax was car- 

 ried on from October, 1901, to its death in 



July, 1903, at the 860th generation. A 

 record of the daily rate of division of the 

 four lines of the culture was kept, and 

 showed that the organism, when subjected 

 to a uniform diet of hay-infusion, passes 

 through marked periods of greater and less 

 dividing activity. The first period of great 

 loss of vitality occurred at about the 230th 

 generation and the culture was on the verge 

 of extinction, when it was 'rejuvenated" by 

 the use of extract of beef. The second de- 

 pression-period resulted in the death of the 

 culture. A study of some two hundred 

 permanent preparations of individuals 

 showed that morphological changes occur 

 during the life-cycle. A vacuolization of 

 the cytoplasm appears first, and then dis- 

 tortion and fragmentation of the maero- 

 nucieus, and reduplication of the micro- 

 nuclei beyond the normal number when the 

 vitality is at the lowest ebb. A similar 

 study was made on four other cultures of 

 hypotrichous ciliata and the results com- 

 pared. 



The Groups and Distribution of the Nortli 

 American Species of Diaptomus: C. 

 Dv^'iGHT Marsh, Ripon College. 

 Diaptomus is a genus of considerable in- 

 terest, as it forms the greater part of the 

 plankton that is available for food for fish. 

 It is assumed that the genus is derived 

 from marine ancestors, but it has no very 

 close relatives. Thus far no attempt has 

 been made even to arrange the American 

 members of the genus in groups. A study 

 of the distribution of the species with our 

 present knowledge throws some light on 

 the probable phylogeny of the group. 

 There are now known thirty species. The 

 distribution is in general one of latitude, 

 with the greatest number of species in the 

 mountain region of the west. A study of 

 the distribution, with a comparison of 

 structural characters, leads to a grouping 

 of the species under four heads, the 

 tenuicaudatus group, probably, being the 



