LABRAL GLANDS OF STMOCBPHALUS 229 



between the two tables as a basis on which to postulate 

 similarity between the two sets of experiments, of which the 

 tables are representative, depends solely on the accuracy of 

 the first table. While it is admitted that the second table is 

 no doubt comparatively accurate, it must be emphasized that 

 in the first table referring to the abnormal curvature of the 

 carapace, the presence of a reaction in F 3 generation was 

 indicated by an increase among only forty-seven individuals, 

 of 6 per cent, over a normal ratio — and in measuring this ratio 

 an error could be made of as much as 20 per cent. — the 

 average error according to a table quoted by Agar to show this 

 inaccuracy is roughly 10 per cent. It appears very uncertain, 

 on such data, to make the definite statement that there was 

 a ' very decided reaction '. The repetition of these results of 

 Agar was abandoned because, in the individuals used, the 

 inaccuracy of the measurement of the ratio which indicated 

 the extent of the abnormality was even more marked than in 

 those used by Agar. 



It may be mentioned here that Agar merely stated that the 

 food producing the abnormality was a ' culture of protophyta 

 grown in a mixture of cowdung, soot, and water '. It was 

 found that the abnormality can be produced by feeding a 

 culture containing no other protozoon than a species of 

 Chlamydomonas. Also, contrary to Agar's finding, it 

 was not found possible to produce the abnormality in Simo- 

 cephalus exspinosus. 



In the experiments recorded here there seems no evidence as 

 to how the neutral red disappeared. As Agar suggests for 

 cases of parallel induction, it may have disappeared by mere 

 dilution caused by the increase in the bulk of the protoplasm 

 without a corresponding increase in the amount of the stain. 

 Partly the stained matter may be oxidized or changed in some 

 way into a colourless material which may or may not be 

 excreted ultimately. 



These experiments on intra vitam staining were carried 

 out before the mechanism of feeding was closely studied. The 

 latter investigation made it obvious that, as already stated, 



