394 SCIENCE PROGRESS. 



history, Mr. Comber (6) has placed some early observa- 

 tions by Lauder and others together with his own acute 

 investigations, with the result that there is now a firmly 

 established knowledge of the production within diatoms of 

 other forms with different sculpturing of the tiny shells, 

 probably in fact a dimorphism which may or may not occur 

 in alternate order. Mr. George Murray (7), working at sea 

 on the Ga7'-land on behalf of the Fishery Board for Scotland, 

 independently established the same point by observation 

 of the living forms and carried the matter further. He 

 points out that the internally produced form (dealing with 

 different genera from those of Mr. Comber) may itself 

 multiply indefinitely in the sea before recurring to the 

 parent form, and that not one merely but groups of two, 

 four, eight, or sixteen of such forms may be produced w^ithin 

 the parent, and that these are in certain cases not different 

 from the parent but exactly resemble it. These details, im- 

 portant and utterly unexpected though they be, absorb the 

 interest of the botanist more than that of the oeneral 

 student. Just as the great work of Russell, Fischer and 

 others on the Bacteria of the sea has furnished us with a 

 missing link in the chain of economic relationships of 

 organisms, so another such link has been found, or rather 

 strengthened, in Mr. George Murray's observations. Re- 

 ference has been made to the observations of Mr. R. 

 Brown on the occurrence of diatoms within the intestinal 

 canals of the animals which form the food of whales, and 

 their presence within many sea animals from full-grown 

 fishes downwards is a well-known fact. That the plankton 

 or surface floating plant-organisms are the basis of animal 

 nutrition in the sea has lono- been obvious, but direct obser- 

 vation has been wanting. Mr. Murray made a minute 

 examination of the substances digested by the Copepoda 

 and other small Crustacea, which themselves form a large 

 part of the food of fishes, with the result that he has dis- 

 covered such substances to consist almost exclusively of the 

 chromatophores or colouring granules and fine fragments of 

 the siliceous shells of diatoms. Professor Mcintosh antici- 

 pated this observation, having made a brief record of the 



