92 CAROLINE BURLING THOMPSON 



and food from the workers and become the 'large headed' or 

 sterile forms. 



Holmgren's own words are: 



Wenn nun der oben gegebene Zusammenhang zwischen Fiitterung 

 und Exsudatabsonderung gilt, indem die Menge der Exsudatabsonderung 

 die Art der Fiitterung bestimmt, so scheint es selbstverstandlich, dass 

 die Exsudatabsonderung mit der Kastenbildung in nahem Zusam- 

 menhang steht. Denn Grassi und Sandias haben gezeigt, dass die 

 Fiitterung wahrscheinlich als Faktor der Kastenbildung anzusehen 

 ist. Diese Auffassung ist auch allgemein angenommen worden. 



Holmgren also states that food may be the determining cause 

 of sex, more food producing females, less, males. 



Feytaud ('12) has made a careful and very valuable study of 

 the common European termite, Leucotermes lucifugus Rossi, 

 supplemented by some comparative work with certain other 

 species. In regard to the origin of the castes he states that the 

 newly hatched nymphs are all alike, and that the differences 

 between the future neuters and sexual forms appear only after 

 the first molt, which takes place when the nymphs have attained 

 a length of 2 mm. and have twelve antennary segments. In 

 agreement with Grassi, Feytaud recognizes, after the first molt, 

 the large headed nymphs destined to become workers and sol- 

 diers, and the small headed nymphs which will develop into the 

 sexual forms. The cause of the differentiation of these two 

 forms, and of the differentiation from them of the future castes, 

 is, according to Feytaud, the treatment and food given by the 

 parents or the adult workers to selected groups of the developing 

 nymphs. 



But, although Feytaud accepts the prevailing view that food 

 and care determine the castes, in his careful and exact study of 

 the internal anatomy of the youngest forms, there is evidence 

 which gives strong support to our second view that the castes 

 are determined before hatching. This evidence is to be found in 

 Feytaud's statement that, possibly, two types of nymphs — 

 with differences in the degree of development of the sex organs — 

 exist from the time of hatching. 



