ZOOLOGY. 

 A posthumous paper on Myxospridia by M. Prosper Th£loh an has 

 recently appeared prefaced with a short account of the authors's 

 scientific career by E. G. Balbiani. The Memoir, intended as a thesis 

 for the degree of Doctor of Science, while complete in the essen- 

 tial parts, lacks the final chapter in which the author intended to 

 indicate the relations of the different genera and families of the Myxos- 



Briefly stated, Myxosporida are parasitic Sporozoa found living in 

 certain fishes, batrachians and reptiles. They have also been observed 

 living in various arthropods, notably spiders and crustaceans. Certain 

 families are limited to vertebrates host : Myxobolidie and Chloromyx- 

 idse. It is to the latter forms that the author devotes his paper. 



It has long been known that the Myxosporida of the vertebrates 

 assume two forms; one, a small ameboid body swimming free in the 

 liquid which contained in certain organs, chiefly the gall and urinary 

 bladders, and a second form which is found distributed in compact 



may be harmless to the host, or on the other hand, give rise to grave 

 disorders, resulting in the death of the animal which they have 

 invaded. 



The free swimming species are variable in form, the most common 

 one being that of an elongated cone the base of which corresponds to 

 the anterior extremity ; others are almost spherical. It is, however, 

 difficult to decide upon a definite species form, since each individual 

 exhibits such extraordinary polymorphism. The organisms found in 

 the tissues are generally spherical. 



Ordinarily these parasites are colorless, but yellow ones have been 

 seen, and a few green ones are reported. 



In dimensions, as in form, there is great diversity. The free swim- 

 ming species are from 10 or 12,*. in diameter to 5 mm. in diameter. 



Reproduction is accomplished by sporulation, and, probably, also 

 by fission. The protoplasmic body of the Myxosporida is plainly dif- 

 ferentiated into a peripheral zone, ectoplasm, surrounding the central 

 sarcode, endoplasm. The former functions as a protection for the 

 latter and, also is capable of putting out pseudopodia which act as 

 organs of locomotion or fixation. These pseudopodia are localized in 

 certain species, in others they appear at random. They take no part in 

 the phenomena of nutrition. 



The endoplasm of young individuals appears homogeneous, but in 

 older ones there are found, in some cases, certain products of differentia- 



