CURTIS ; LIFE HISTORY OF PLANARIA MACULATA. 
taken as many precautions as seem to me necessary to guard against 
the possibility of my dealing with two distinct species or two varie¬ 
ties of a species where but one has been previously recognized. 
There are no external differences between the worms of the sev¬ 
eral localities beyond the variations in color whidh one might expect. 
Specimens from a single locality will often differ more in color than 
any specimens collected from localities where the life history is 
entirety different. So far as I can ascertain from the most care¬ 
ful measurements, the shape of the head and other proportions are 
identical in all the localities. What I have learned regarding the 
changes in the several localities is as follows: — 
Locality 1. All the worms are large and sexually mature in the 
spring. During May and June they lay their eggs. In July the 
young and adults are found together and are easily distinguishable. 
In the latter part of July and during August the adults are found 
with their reproductive organs in all stages of degeneration and 
sometimes show evidence of fission before these have entirely dis¬ 
appeared. Toward the end of August and in early September no 
reproductive organs are to be found in any of the individuals and 
the old ones, if still alive, cannot be distinguished from the young. 
They are found during these two months reproducing by fission to 
a very considerable extent. In the fall the fission stops and all the 
individuals develop reproductive organs in preparation for the egg 
laying of the next spring. This has been observed for three years. 
Locality 2. The same as locality 1, save that I have never seen 
any satisfactory indications of fission. This is then, as far as the 
observations go, an exclusively sexual locality. Observed the same 
course for three years. 
Locality 3. A period of very active fission was observed during 
June, July, and August. No reproductive organs have ever been 
discovered, but a single egg capsule was once found which shows 
that sexual individuals do sometimes occur. Observed for one vear. 
4 / 
Locality 4. A period of very active fission, as in locality 3, which 
begins in June and lasts until the last of September, but no repro¬ 
ductive organs or traces of the egg capsule have ever been seen. 
Specimens examined in November and again in May showed no 
sign of reproductive organs. Observed the same for two years. 
The account of the fission in Planaria macidata given by Randolph 
(’97) was based upon worms from this locality. 
