94 NEW YORK STATE MUSEUM 



streak. Five days later one embryo had a length equal to one-half 

 that of the mother larva, the embryonic adipose and mesodermal 

 tissue were rather distinct, while the adipose tissue of the mother 

 larva was largely absorbed. On the 22d the form oi the mother 

 larva was distinctly modified by the obliquely-lying young, each 

 with a length approximately three-fourths that of the parent. The 

 next day we observed the mesoderm, composed of irregularly ar- 

 ranged, subhexagonal cells, accompanied by the appearance of 

 incipient ocular spots in various embryos. The tip of the head 

 became fuscous by the 28th and on January 5th, slight movements 

 of the embryos were observed. Owing to the reduced oxygen 

 supply, due to the larva being in a practically sealed cell, the em- 

 bryos experienced difficulty in escaping. One was observed Jan- 

 uary 9th with the seven anterior segments protruding from the 

 posterior extremity of the mother larva, remaining in the same 

 position and nearly motionless the three following days. The cell 

 was opened January 14th and the mother larva given air, but the 

 action was apparently too late, as the young failed to revive. There 

 appears to be sufficient oxygen in the tissue of the mother larva to 

 permit the embryos to become fully developed. 



Methods. The material taken in October was kept in ordi- 

 nary fruit jars for a time, some of these at least being allowed to 

 become rather dried. There was very little or no multiplication. On 

 November i8th small pieces or slivers of somewhat dried wood con- 

 taining these larvae were either clamped directly to ordinary 

 microscopic slides or laid between two held together by means of 

 light wire clips. These portions of infested wood were kept on 

 moistened blotting paper in a dark, tin box, being examined every 

 two or three days. Large, white mother larvae were produced from 

 time to time and occasionally considerable colonies of small young 

 were observed in the vicinity of the empty skins of mother larvae. 

 Such preparations enabled us to keep track, not only of a colony 

 but, by noting the location of quiescent larvae, even of individuals. 

 Later this series was supplemented by a few fragments of wood 

 laid upon microscopic slides, covered with large, square cover glasses 

 and the margins more or less perfectly sealed with vaseHne. The 

 cell thus formed was kept moist and sometimes flooded with water. 

 Under such conditions full grown white larvae, quiescent larvae and 

 small, white or yellowish larvae were also studied. They apparently 

 thrived for one week at least. Finally we selected a series of small, 

 yellowish, active and quiescent larvae, placed them in water cells 



