INTESTINAL PROTOZOA OF TERMITES. 183 



Reticulitermes flavipes, i.i mm. long, although externally all 

 alike, could be differentiated by their internal structures into two 

 distinct type-, namely, (a) reproductive nymphs, from which 

 develop the three fertile adult castes, and (b) the worker-soldier 

 nymphs, from which develop the two sterile adult castes. By 

 the time the- reproductive nymphs had attained a body length 

 of i.} 1.4 mm. tlu-y could be differentiated by their intern. il 

 character- into nymph- f the first form and nymphs of the sea >nd 

 form, which de\ eloped, finally, into the two re-pecti\e repro- 

 ducii\f adul' 5 'Her and worker nymph- could be dif- 



ferentiated, internally. \\hen they had attained a body length 

 ot .V75 mm. Nymphs of the third form could not be differentiated 

 until a body length < .f 4 mm. was attained. 



-\rr.il intermediate forms have been discovered by various 

 in\i tors, intermediates between the first and second form-, 



three fertile -oldiei- I l< ith, 1902)', and others; but the-e need 

 not be . on-ideied 1;. 



Tin- ti\ ' cur in most termites. Known exception- are 



as fol]o\\-: i In- third form reproductive caste occurs in k-w, if 

 . of iht I '( Tiniti'l i ; in fact none have been reported trom the 

 Nearcti< gem this family, and it is doubtful it" thi- ca-tr 



urs in an\ i^enus of the Termitid;e. Apparently thi- caste 

 ha- ln-t-n lo-i in this, the most highly specialized, famiK of ter- 

 mite-. The third lOmi is less common than the first .m<l -ecoiid 

 in Reticuli Jl wipes, but in Termopsis it is more c..mmon 



than the tir-t .md second form. Reticulitermes is about midway 

 bet\\eeu the most primitive and the most highl\- >p iali/ed 

 termite-. / \ > n:n/'\is is a primitive genus. A true \\oiker caste 

 i- not pie-cut in Termopsis and Neotermes, but a lar^e-hc.nled 

 \\oikir-like rejiroductive form is present. Two genera. Kalo- 

 ternifs and ('ryptotermes, have no worker caste. The ^enu- 

 . 1 it/>f>.'' has no soldier caste. 



Grassi calls the first forms "true" or "perfect insects," or 



1 \\ 'Social Life among the Insects. Sci. D M nthly. 16, 1923, p. i 



.md workers are normally strrilr. hut soim-timus tlu-y become 



intiii- .iu.1 pp'l'ulily on such occasions n-i>r..(li:- thfir n\vn > Snj-der 



(personal communication) soys Heath now admit-: IK- \va> \\rniig. Also experi- 

 ments \\hiih 1 have conducted recently reveal the fact that the soldiers of at least 

 :.il, .i;id pmhaMy all. \>'I>phagus termites cannot live to themselves 



vvlu-n K'VI 'ii thi-ir iiuimal diet <if wood. 



