292 THE ENTOMOLOGIST. 



ichneumons, Pteromalus sp., and others, died of the disease in 

 this stage. 



The brood of the most abnormal female, reared with the 

 greatest care, produced only fifty-two pupFe, which are included 

 in the 493 before mentioned. 



On July 21st the imagines emerged till 27th, altogether two 

 hundred specimens ; amongst them the first specimens of the 

 brood of the most abnormal female. All these specimens were 

 entirely and thoroughly normal. On July 28th appeared one 

 variety (cfr. Exp. zool. Stud. pi. v. fig. 4), and on July 31st and 

 Aug. 1st, each one more, differing from the normal form, but not 

 very abnormally. On Aug. 5th, among the last imagines from 

 this experiment, a very aberrative specimen emerged (cfr. Exp. 

 zool. Stud. pi. V. fig. 5), as the previous three, also the progeny 

 of the most abnormal female. It was also a male. 



The result of heredity experiments with abnormal forms 

 obtained by the frost experiments — the whole material from 

 emerged imago through egg, larva and pupa to imago being 

 treated as far as is known to perfectly normal conditions — is as 

 follows : — 



1. Two of the ten females experimented with did not produce 

 offspring. 



2. The small portion of the broods of probably seven females 

 which reached maturity reverted entirely to the normal form. 



3. An eighth pair, from which only forty-three specimens 

 were obtained, resulted in one well and three slightly developed 

 aberrations, in the direction of the parental aberration. 



4. These four individuals are all males. 



5. Only the most abnormal female — the thirty-two males, as 

 already stated, were about of equal merit as far as their abnor- 

 mal characters are concerned — transmitted its newly acquired 

 characters more or less to a small portion of its offspring. The 

 possibility of transmitting these anomalies seems to be condi- 

 tional on the extent of the anomaly. 



6. As this experiment, on account of the outbreak of disease, 

 was very incomplete, it is desirable to repeat same again, with 

 plenty of material. 



However, the facts obtained may be considered of great im- 

 portance for estimating the influence which natural factors con- 

 tribute to the alterations of living organisms, especially when one 

 considers that the same individual which we have here produced 

 from the brood of abnormal parents never occurs amongst 

 countless thousands of creatures of normal parentage, which 

 have been subjected to exactly the same conditions. 



(To be continued.) 



