BRAIN OF THE 'WHITE ANT' 571 



In the head of the true adult (fig. 9, ox.) the ocelU may be readily 

 seen as small colorless spots which stand out sharply from the 

 surrounding brown skin, but in the heads of nymphs (figs. 8, 10), 

 whose skin is not pigmented, the ocelU are not visible except in 

 sections. 



The ocelli are of a very simple and primitive tj^pe, Hesse 

 ('01 b), without a lens and with httle or no pigment. The outer 

 surface of the hypodermis above the ocelU is slightly convex, 

 the inner surface is very concave, the latter caused by the sudden 

 thinning of the inner cuticula, and in this concavity the bulb- 

 hke ocelli are situated. In general contoui* the ocelli resemble 

 the tactile buds found in the skin of Amblj'stoma punctatum. 

 The visual cells are long slender and curving, with spaces between 

 their bases. As to the finer intracellular structure, I am not 

 prepared to make a statement at this time. I shall also leave 

 for further study the question whether the distal ends of the 

 visual cells lie between the hypodermal cells, a primitive position, 

 according to Hesse, or whoUj', and secondarily, beneath them; 

 although the first view would seem to be upheld l^y my present 

 material. 



In a frontal section of the anterior part of the brain of a 

 nymph with long wing pads, the oceUi (fig. 13, oc.) may be seen 

 on each side of the section, just beneath the hypodermis, and 

 covered by a thinner layer of cuticula, the inner cuticula, i.cu., 

 being absent at this point. From the ocelli the slender ocellar 

 nerves, lying just outside the brain sheath, run in toward the 

 median line and enter the nerve cell layer of the protocerebral 

 lobes just above the anterior roots of the mushroom bodies. 

 Passing down into the intercerebral region, the ocellar nerves 

 (figs. 15 to 18, oc.n.) run backward and finally enter the dorsal 

 surface of the protocerebral lobes just behind the posterior 

 dorsal commissure and in the same frontal section as the fontanel 

 nerve from the frontal gland (fig. 19, oc.n., f.n.). At no point 

 along their entire length do the ocellar nerves expand into ocellar 

 lobes such as are present in the bees and ants. After my first 

 cursory examination of the brain sections of L. flavipes, I was 

 inclined to assign the role of ocellar lobes to the large lobes. 



