496 A. W. BELLAMY 
Experiments with HCl 
In all of the experiments involving HCl and NaOH the solutions were 
made up from freshly prepared (in the case of HCL) n/10. These stock 
solutions were diluted with an amount of well-water that would give, 
theoretically, the strength of acid or alkali stated for each experiment. 
And while, in the case of HCl the concentration of acid was certainly lower 
than that stated due to the presence of carbonates and salts in the well- 
water, the solutions were always prepared in the same way, so that, 
regardless of the actual concentration or of the hydrogen ion-concen- 
tration, the figures representing the strength of acid are sufficient for 
purposes of comparison. It will be understood, then, that the con- 
centration given, e.g., n/5000, is relative, indicating merely the amount 
of n/10 stock solution added to a given quantity of well-water necessary 
to furnish a theoretical n/5000 solution. We hope later to report a. 
series of experiments similar to these in which the actual hydrogen-ion 
concentration is known. In all experiments liter Erlenmeyer flasks 
were used. They were filled with the solution and stoppered. Con- 
trols were run parallel in stoppered flasks of well-water. Solutions 
were changed daily unless otherwise noted. 
Figures 15 to 21 illustrate seven embryos from experiment 130.3. 
The eggs when in early gastrula stages were placed in n/750 HCl and 
after twelve hours were removed to water. The figures show their 
condition eighty-one hours later. They show just about the same 
abnormalities and the same range of variation in type as is seen after 
treatment with a great variety of other agents and conditions. EKm- 
bryos of much this same type were obtained in three other series of 
HCl experiments, furnishing approximately the conditions noted above. 
One curious consequence of the HCl treatment in low concentrations 
was a very marked acceleration of development. Without attempting 
to decide at present whether the acceleration is due directly or indirectly 
to the HCl as such, the results are perfectly clear cut and definite. 
Both Professor Child and myself have obtained these acceleration 
forms independently and repeatedly. Furthermore, there is a ten- 
dency for the embryos to become megacephalic under such conditions 
and often the tails, ventral suckers, and gills are unusually prominent. 
In other words, the acceleration is more or less differential. The em- 
bryo apparently does not simply develop more rapidly as a whole, 
but certain regions are more accelerated than others, viz., the same 
regions that are most inhibited under conditions that markedly retard 
developmental processes. 
Experiment HCI-C. 1. 1/5000 HCl. Eggs two to four-cell stage 
at beginning of the experiment. 
30 hours in HCl. Early gastrula. In advance of control. 
60 hours in HCl. Neural fold stages. Control, small yolk plug 
stages (figs. 30, 31). 
72 hours in HCl. Blastopore closed and embryos beginning to 
elongate. None of the control embryos elongating yet. 
