230 Phylum Art hr op oda 



against dust. It was placed in a cool laboratory near a north window 

 and shaded from other windows. By late May almost no algae have 

 appeared and there has been no putrefaction. The death of various 

 insect larvae and of some individuals of the amphipod, Dikcrogammarus 

 jasciatus, has caused no evident upset in the equilibrium. Instead of the 

 animals being balanced against plants they are balanced against the 

 atmosphere. The aquarium contains a considerable number of % to 

 Y 2 grown Aselli, offspring of the original individuals, and a variety of 

 Entomostraca, including a few cyclopids which have maintained them- 

 selves without noticeable increase in numbers. 



MAINTENANCE OF LAND ISOPODS 



John L. Fuller, Massachusetts Institute of Technology 



MOST woodlice are easily maintained in the laboratory on moist 

 soil rich in humus. A wooden box 18" x 18" x 6" with a tightly 

 fitting glass or wood cover will accommodate about a thousand animals. 

 Land isopods should not be overcrowded, or molting individuals will be 

 killed by their companions. In general, species should not be mixed, 

 for the weaker species will be eliminated. If pieces of rotten wood and 

 small stones are placed on the soil, the woodlice will congregate under 

 them, making it easy to collect animals when desired. Water is added as 

 necessary. 



A temperature of from 20 to 25 C._ is favorable for most species. 

 Animals collected in the fall and kept between these temperatures will 

 bear their first brood of young in February. Mating takes place readily 

 when the two sexes are together; the fertilized females may be picked out 

 since each carries its eggs in a ventral thoracic pouch. From 12 to 200 

 young are released in about three weeks, the rate of development and 

 number of young differing for different species. 



These animals appear to find sufficient nutriment in the organic matter 

 of the soil, but will also eat slices of raw potato avidly. The nutritive 

 requirements of the young are similar to those of adults. 



Greatest success has been obtained with Oniscus asellus, Porcellio 

 scaber, Trachelipus rathkei, and ArmadiUidium vulgar e, though other 

 species do nearly as well. Porcellio pic t us is less hardy, and apparently 

 requires lime. Trichoniscus may be kept on wet moss in glass jars with a 

 little water in the bottom. Particular care should be taken to keep 

 Porcellio and Trichoniscus in a cool place. 



There appears to be no reason why healthy cultures may not be 

 maintained indefinitely with a minimum of care. Lack of moisture is 

 the chief danger to be avoided. 



