IN TROD UCTOR Y. 23 



important characters by the admixture of alcoholic 

 preservative solutions. I can attest, from personal 

 and long-continued experience, that it is simply im- 

 possible to arrive at a correct knowledge of the 

 characters of the recent unadulterated material from 

 material that has been thus preserved. The fact is 

 that there is as marked a distinction between the 

 aspect of pure fresh sponge-protoplasm, for example, 

 seen instantly on its arrival at the surface, and its 

 aspect a very brief period afterwards, as there is 

 between living Foraminifera and Polycystina of the 

 open ocean immediately after capture, and after they 

 have been consigned to some preservative solution. 

 In addition to other important changes produced in 

 the protoplasm of the Protozoa, both marine and 

 freshwater, by being long kept or preserved in such 

 preservative solutions as alcohol, when calcareous 

 matter exists in solution, molecular changes take 

 place, the normally homogeneous protoplasm then 

 frequently being converted into minute globular 

 masses, which, when seen under the microscope 

 resemble sago-grains in miniature, and may readily 

 be mistaken for molecular granules of the organism 

 within or upon which they occur. I can produce 

 specimens of Polycystina, and, to a certain extent, of 

 Foraminifera, the rich and varied brilliancy of colour 

 in which has been retained for years, in some cases, 

 even when mounted in balsam ; but there all identity 



