and Laboratory Methods. 162^ 



CURRENT ZOOLOGICAL LITERATURE. 



CHARLES A. KOFOID, University of California. 



Books and Separates of Papers on Zoological Subjects should be Sent for Review to Charles A 

 Kofoid, University of California, Berkeley, California. 



Rhumbler, L. Nordische Plankton-Foramim- This is one of a series of papers on the 

 feren. No. XIV aus Nordisches Plankton . . r i i i r 

 herausgegeben von Prof. Dr. Karl Brandt. various organisms of the plankton of 

 .32 pp., 33 fig- ™ Texte. Lipsius und Tischer. the North Atlantic Ocean by special- 

 Kiel, IQOI. . , , , ^ , , 



ists, the whole to form a volume when 

 completed. It is the intention to include all forms, both plant and animal, known 

 to occur in the plankton north of 50° north latitude. The Foramhiifera of 

 the plankton as a rule possess many chambered calcareous shells wound in a 

 spiral which in Orbulina is covered by an outer surrounding chamber. The 

 pelagic species thus belong to the Rotalidte with the single exception of Chilos- 

 fomella, an elongated form devoid of spiral structure. As elsewhere within the 

 group no distinction between ectoplasm and endoplasm can be detected. Many 

 of the pelagic species contain an orange or yellowish pigment which seems to 

 depend upon the food of the individual. The genus Pulvi?iulma feeds upon dia- 

 toms and vadiolarians, while Globiger'ma apparently confines itself to the Cope- 

 poda, for the partially digested muscle fibres of these animals are to be found in 

 the protoplasm of members of this genus. The absence of the skeletal parts of 

 the Copepoda in the protoplasm is explained by the extrathalamous capture and 

 partial digestion of the prey. The protoplasm of certain pelagic species contains 

 a peculiar network of threads resembling a mycelium, though apparently not of 

 parasitic origin. These problematical structures stain a bright blue in methyl 

 green-eosin and are apparently of a gelatinous composition. The suggestions 

 are made that they may serve as supports for pseudopodia, or that they may be 

 (in Globigerind) the early stages in the formation of a gelatinous covering about 

 the shell. The genera Globigerina and Orbulina harbor the commensal alga, 

 Zooxanthella. 



The nucleus of all the species examined (by the sectioning method) was 

 single, and in Globigerina fixed in sublimate exhibits a peculiar alveolar struc- 

 ture without chromatin network, while in Pulvinulifia the typical nuclear struc- 

 ture is to be found. The absence of developmental stages in the plankton mate- 

 rial leads the author to suggest that reproduction takes place in the bottom 

 waters. The collections examined contain some hints of an alternation of gene- 

 ration in the pelagic types, of embryos within the maternal organism which 

 become megaspheres, and of swarming individuals which become microspheres, 

 the latter, however, developing into the larger type of adult. This may account 

 for some of the variability in the groups which the author recognizes in the large 

 number of synonyms which he lists. Adaptations to the pelagic life are to be 

 found in the spinous prolongations of the shells which reach two to three times 

 the diameter of the shell body ; also in the gelatinous coverings of some species. 

 These structures increase the floating capacity of the organism. 



