10 'Journal of Comparative Neurology and Psychology. 



that the eggs could be removed with a pipette at desired intervals 

 without disturbing the male parent. As segmentation had not 

 begun when the nest was found, no eggs were removed until the 

 following day at 3 o'clock, when the blastoderm was found to 

 cover about half the yolk. Forty-nine hours after the nest was 

 found eggs were removed and as the embryo was sufficiently 

 developed to render the presence of taste buds possible, series 

 were taken at intervals ranging from four to fourteen hours up 

 to the eighth day, and on the ninth day a thirty-one hour series 

 was taken when the eggs in the nest were exhausted. After ex- 

 amination it was found that in the oldest embryo of this series 

 buds were not present back of the operculum on the body and 

 later series were taken the following year. Since no nests were 

 found in which the eggs were being fertilized, so that the exact 

 age could be determined, these embryos were arranged accord- 

 ing to measurement rather than age. The oldest embryo of 

 the first series was 9.4 mm. in length, and the later series were 

 selected so as to complete this, embryos being cut which measured 

 II, 14!, 15J, lyi and 20J mm., respectively. 



In the first series five lots were taken for each stage and fixed 

 in the following fluids, {a) Hermann's, {b) Fi.emming's, both the 

 weak and the strong solution, (c) a chromo-aceto-osmo-platinic 

 mixture, and (d) Zenker's fluid. 



A number of stains w^ere tried but Heidenhain's iron hasma- 

 toxylin after Zenker gave the best results. This stain gives 

 a sharp differentiation to the taste buds, sometimes staining the 

 sense cells and sometimes the supporting cells. In the ear and 

 lateral line organs it usually stains the pear shaped sensory cells 

 quite black, thus rendering the separation of the neuromasts from 

 taste buds quite easy. 



Every alternate series beginning with the earliest was cut, but 

 no buds were found until series K' (113 hours). This is about 

 24 hours before hatching, the incubation period being about six 

 days. 



The earliest buds to appear are of course very immature, but 

 little or no difficulty was experienced in recognizing them as soon 

 as the first rudiments appeared. The only organs with which 

 they could possibly be confused would be the teeth in the oral 

 and pharyngeal cavities and the neuromasts in the cutaneous 

 regions. The teeth appear first as invaginations of the Malphigian 



