Vol. XXXVI. June, 1919. No. 6. 



BIOLOGICAL BULLETIN 



THE DEVELOPMENT OF THE CASTES OF NINE 



GENERA AND THIRTEEN SPECIES OF 



TERMITES. 



CAROLINE BURLING THOMPSON, 

 DEPARTMENT OF ZOOLOGY, WELLESLEY COLLEGE. 



In a former paper (Thompson, 1917), the writer showed that 

 the newly hatched nymphs of the termite Reticulitermes flavipes 

 Kol., i.i mm. long, although externally all alike, are differen- 

 tiated by internal structural characters into two distinct types 

 (a) reproductive nymphs and (b) worker-soldier nymphs from 

 which develop (a) the three fertile adult castes, the reproductive 

 forms, and (b) the two sterile adult castes, the workers and the 

 soldiers. It was further shown that when the reproductive 

 nymphs have attained a length of 1.3-1.4 mm. they are differen- 

 tiated by internal characters into "nymphs of the first form" 

 and "nymphs of the second form," which develop finally into 

 two of the three adult reproductive castes; 1 at a much later 

 period, when they have attained a length of about 3.75 mm., the 

 worker-soldier nymphs become differentiated by internal char- 

 acters into the worker and the soldier nymphs. 



Bugnion (1912, '13) states that the soldier (nasutus) of 

 Eutermes lacustris, a new termite species from Ceylon, is dif- 

 ferentiated at the time of hatching, and may be distinguished 

 from the other newly hatched nymphs by both external and 

 internal structures, namely: the frontal process (corne frontale) 

 and the large frontal gland. 



These observations of Bugnion are not in accord with the work 

 of Knower (1894) who states that the nasutus of Eutermes 

 rippertii (?) since identified by Mr. N. Banks as E. pilifrons 



1 The development of the third, wingless, reproductive caste of R. flavipes has 

 not been worked out. 



379 



