76 CHAS. W. HARGITT. 



the Scrpulidip, which like Spirographis presented only their gills 

 to the light, bent them strongly upward" ('90, "Gen. Phys.," 

 Part I., p. 102), and he continues, "within six weeks the entire 

 block was covered with tubes which curved upward; not a single 

 individual had continued to grow in the original direction," and 

 presents a figure in illustration. There is apparent discrepancy 

 between the latter and the statement " not a single individual, 

 etc.," for in the figure about as many appear to "continue to 

 grow in the original direction" as have "curved upward." My 

 own experiments show a reasonable conformity to Loeb's figure, 

 but the ratio of tubes indicating reaction is very much smaller. 

 Figs. 2, a, b, c, are photograph reproductions, and may therefore 

 be taken at their face value, and they certainly fail to show any 

 such response as claimed above. For example, it w'as found by 

 actual count of a colony comprising hundreds of tubes which 

 had been under test for more than a month that only about 

 twenty tubes had definite curves toward the light, a similar 

 number had shown lateral curvatures, and a smaller number 

 had curved downward; but the larger number "had continued 

 to grow in the original direction." A smaller colony which had 

 been under test for twenty-five days under particularly favorable 

 light conditions showed a slightly larger response toward the 

 light; but here also the number was relatively small. Another 

 colony was placed in an aquarium which was covered on three 

 sides and above with a black hood. After a test of nearly two 

 months (January 23 to March 18), it was found by a careful 

 estimate from counting that at most only aboni Jo per cent. 

 showed any possible light reaction ; while by far the greater num- 

 ber either continued to grow in tin- original direction or showed 

 curvature laterally or downward. Tin- colony was submitted to 

 two others working at the laboratory, I)r. Butler, of University 

 College, Dublin, and 1 )r. S. k. Williams, of Miami University, 

 Ohio, both of whom made the per cent, ot light reaction much 

 lower than my own. 



A very interesting and, 1 believe, significant leature of growth 

 in this species came to light during the observations, nainelv, it-- 

 very erratic, or discontinuous character. Some individuals 

 showed a very prompt and rapid growth at lir>t and later its 



