114 PLANARIA. 
Only the head of fig. 11 survived mutilation, also on September 14 ; 
it had become nearly symmetrical on October 24, by acquiring a new tail. 
But the brown colour of the original was now converted to grey, fig. 16. 
Of a third specimen, subdivided into three portions, all had become 
entire and nearly symmetrical animals in twenty-eight days. The middle 
portion had regenerated both a head with its two eyes, and a tail. The 
lowest section had regained a head and eyes ; and the highest, preserved 
by its ova, had acquired a tail. Thus the more prominent parts of the 
external organization were multiplied from the original two to six, by 
experiment.—Fig. 17, head, with a regenerated tail ; fig. 18, middle sec- 
tion, regenerating both head and tail; fig. 19, tail, having regenerated a 
head. 
That similar redintegration would restore the integrity of mutilated 
animals, I had ascertained many yearsago. These observations, together 
with the skilful and successful experiments of Dr James Rawlins John- 
son, render the farther prosecution of the subject, to which I personally 
feel peculiarly averse, altogether unnecessary. 
These Planariz dwell in springs or fresh-water rills, under stones, or 
involved in leaves. They are exceedingly sensitive of atmospherical al- 
terations. When the thermometer fell suddenly from 65° to 56°, they 
scarcely continued moving. 
Though numbers inhabited the well above specified, and a rill at a 
short distance from it, none could be found in a pond within 100 yards 
of the former. Several of the lower tribes, however, abounded there. 
Desirous of ascertaining what changes might have taken place 
among these animals after an interval of twenty-five years,*whether in 
aspect or properties, I took some from the same spring-well that had 
formerly supplied me in Linlithgowshire. Now, I hardly recognise the 
precise spot from the numerous changes the neighbourhood had under- 
gone. But the appearance of the animals I succeeded in procuring was 
the same, chiefly slate-grey, of various intensity, a few brownish. Food 
seemed very scanty in their vicinity. The details of my purposed object 
were accidentally defeated. 
