( cii ) 
true in normal surroundings. The generation also included a 
single male specimen of the form tortnosa, which crossed with 
a female decemlmeata yielded hybrids with decemlineata 
dominant. These in succeeding generations split up in 
Mendelian fashion, the tortuosa (extracted recessives) breeding 
true. 
Experiment 4.—The subject of this experiment was the 
tropical species Leptinotarsa muUitaeniata. Here, again, the 
parent beetles were exposed during the first period of egg- 
laying to artificial conditions of heat and humidity, while 
during the second period the surroundings were normal. The 
results obtained were analogous with the preceding. The 
second batch produced nothing but nmltitaeniata for four 
generations, when the experiment ceased. The first batch gave 
together with typical midtitaeniata a much larger number of 
the form melanothorax. The two forms were se})arated, and 
each continued to breed true under normal conditions. 
Experiment 5.—In this experiment, the subject of which 
was again L. nmltitaeniata, the egg-laying period was divided 
into three instead of two portions. The first and third were 
passed under normal conditions, the second under the artificial 
conditions of the last experiment. The first and third 
batches of eggs gave nothing but typical muUitaeniata ; the 
second consisted entirely of the forms melanothorax and 
ruhicunda, each of which continued to breed true. 
Experiment G.—Finally, a similar experiment was tried 
with another tropical species, Leptinotarsa undecimlineata. 
Again the result was the pi’oduction by artificial means of a 
varietal form {angustovittata), which continued to give pure 
descendants showing no tendency towards reversion. 
After these experiments there seems no possible room to 
doubt that the germ-plasm is accessible to external infiuences, 
and that it may by these means be transformed in such a way 
as to give rise to a permanent race of descendants showing 
marked differences from the parent form. 
I will not now stop to discuss Tower’s interpretation of the 
results of these and his numerous other experiments. His 
theoretical views seem to me to differ in value, some being 
weighty in the extreme, and a few, to say the least, question 
