and Laboratory Methods. 1941 



staining by floating the cover-glass up from the mount for examination by the 

 addition of more water, and then carefully pushes it to one side until the animal 

 is exposed. The position of the animal is noted, the slide transferred to a dis- 

 secting microscope and the adjacent debris removed. The animal is then care- 

 fully pushed from its location into an adjacent drop of clean water, the remain- 

 der of the debris is removed and the cover-glass replaced if the living animal is 

 to be studied. When permanent preparations are to be made the animal is 

 transferred to a watch glass, the surplus water removed, and when the pseudo- 

 podia are fully extended it is flooded with absolute alcohol. It is then lightly 

 stained in borax carmine and mounted in balsam. This brings out the nuclei, 

 which are quite essential for modern classification, but renders indistinct the 

 silicious particles of the shell. The latter must be studied in aqueous media. 

 If mounted in balsam of sufficient consistency the animals may be oriented in 

 any desired position by pushing the cover-glass. This is very desirable in the 

 study of the oral aperture, especially in many of the recently described forms. 

 Whole collections may be treated by this method of killing and staining en 

 masse and then assorted as desired. Since Leidy's great work on the Rhizopods 

 no monograph comparable to this of Penard's has appeared. It is indispensable 

 for everyone who desires to work with this group. c. a. k. 



The principle of balanced aquaria has 



Grave, Caswell. A Method of Rearing Marine ^een applied by the author to the rear- 

 Larvae. Science, N. S. 15: 579-580,1902. . . . . 



ing of marine larvse. The plant life is 



supplied by diatoms, which are obtained from aquaria stocked with bottom 

 deposits of sand or mud. The diatoms multiply upon the bottom of such aquaria, 

 and may be gathered with a pipette from the surface of the sand. The larv«e 

 are placed in aquaria of fresh sea water and a dozen or more pipettefuls of the 

 diatom ooze are added. This aquarium is then covered and placed near a win- 

 dow where it is well, but indirectly lighted. The diatoms furnish food and 

 oxygen for the larvae and there is no need for frequent changes of the water. 

 This should be changed occasionally to replenish the salts used by the organ- 

 isms. Larvae thrive in such aquaria, and pass successfully through the critical 

 stage of metamorphosis. c. a. k. 



tiickson, S. J., and Wadsworth, J. T. Dendro- This Suctorian occurs on the gills of 

 cometes paradoxus. Part I., Coniugation. ^ . i ^ ^^ r .1 



Quart. Journ. Micr. Sci. 45: 325-363, pis. Gammarus pukx at all seasons of the 

 17-18, 1902. year, but in greatest abundance in spring 



and fall. A dozen Gammarus placed in a shallow dish with an inch or two of 

 water and some mud and water weed will, within a fortnight, yield a number of 

 conjugating Deiidrocometes. These parasites are firmly attached to the gills so 

 that they may be manipulated readily through the various processes in the tech- 

 nique of preparation without the danger of loss and the difficulty in orientation 

 which attends the preparation of most Protozoa. It is necessary to locate the 

 conjugating pairs upon the gills, which are large enough to be imbedded and cut 

 in any desired plane. Sections were stained in iron-haemotoxylin and in iron- 

 brazilin. Both Deiidrocometes and its ho5t occur in American waters. 



c. A. K. 



