a. On p. 235 T. and K. call it a “serious objection” to ray 
investigations “that starting from a special case (the supposition 
a li = l / a l a t is probably referred to) they represent it as the general 
one and therefore 1 ) must pronounce as abnormal a type occurring for 
normal substances.” 
Here I must remark that I have never represented the special 
case a 12 = a 1 a 3 — from which I only started to make the calcu¬ 
lations feasible — as the general case. Cf. my paper of March 1905 
p. 650, where it distinctly says : “The suppositions 1 ), on which the 
following calculations are based, are consequently the following.” 
Etc. (Cf. there 3). 
Nor have I ever on account of this supposition pronounced type II 
occurring for normal substances (fig. 3 a of the paper of June 
1905; afterwards I called this type III)’ with two cusps R x and R\ 
in the plaitpointline (which also occurs for C ? H # -j- C,H B OH, etc.) 
to be abnormal. I have simply kept the existing nomenclature 
and spoken of an abnormal type , “abnormal”, because the plaitpoint 
line does not run directly from C x to C. , as for type III (fig. 2 a 
loc. cit.; later type II), and because it had first been supposed that 
this so-called “abnormal” type could only occur for abnormal sub¬ 
stances. 
The result of my observations was exactly that this “abnormal” 
type might very well occur for normal substances. 
So far I had not yet got, however, in my paper of May 1905. The 
investigation* begun there was only completed in a subsequent paper. 
Therefore I only wrote on p. 29 loc. cit, (line 9 from the fop): 
“At all events the anomaly of one of the components can 1 ) give 
nse to the occurrence of- this second principal type.” This refers, of 
course, to Kuenen’s well-known experimental investigation concerning 
C »H, + C S H ( OH, etc. 
But in a later paper (evidently overlooked by T. and K.) viz. in 
These Proc. Vol. IX Sept. 1906 (The longitudinal plait) I stated on 
P* 227 as a result of my investigations (four papers in these Proc. 
a nd two in the Arch. Teyler — see p. 227, line 2 — 3 from top): “So 
11 appeared that all the abnormal cases found by Kuenen may already 
appear for mixtures of perfectly normal substances”. (The italics are 
already found in the quoted place). 
This was founded on the investigation, published by me in the 
Arch. Teyler (2) T. XI premiere partie, 1902: Les courbes de plis- 
aement etc. et sur le pli longitudinal. This paper begins with § 1- 
