280 ANNUAL OF SCIENTIFIC DISCOVERY. 



ous akazga. This much resembles, if it is not the same as, the 

 Boumloii jioison, used by the natives of tlie Gaboon for a simihir 

 purpose, the cftects of which are described in "Annual of Scien- 

 tilic Discovery" for 18GD, p. 200. 



ARTIFICIAL PRODUCTION OF MONSTROSITIES. 



The researches of M. Dareste on this subject are referred to, in 

 the "Annual of Scientific Discovery" for 18C9, p. 308; further 

 results obtained are given in " Comptes Rendus" for July and 

 August, 1809. lie here states that embryos developed at rela- 

 tively low temperatures always present organic anomalies, charac- 

 terized, also, by arrest of development of different kinds. Some- 

 times, the cicatricula is transformed into a blastoderm, without pro- 

 ducing an embryo ; this remarkable anomaly confirms the recently 

 expressed opinion of Milne Edwards on the nature of the cicatricula, 

 which he regards as a living being independent of the eml)ryo, and 

 as representing the asexual generations in the cycle of alternate 

 generations. Spinal fissure is one of the most frequent anomalies, 

 and is evidently the result of an arrest of development of the 

 primitive gi'oove. In the very remarkable case of arrest of devel- 

 opment of the primitive groove, the embiyo appears reduced sim- 

 ply to the cephalic region, the rest of the body being more or less 

 completely wanting. In these anomalies, the embr3'0 itself is 

 primitively affected ; others result from arrested development of 

 the amnios, as before observed. Cyclopism is the result, he states, 

 of the juxtaposition, at a certain period of embiyonic life, of the 

 two orbits, or rather their rudiments, at the anterior end of the 

 body. If the orbits are not separated by the ulterior development 

 of the anterior cerebral vesicle, they remain in juxtaposition, and 

 the eyes are united at the moment of their appearance. Arrest of 

 development of the head is often accompanied with arrested car- 

 diac development; the formation of the heart resulting from the 

 union of two blastemas at first separate ; arrest of development 

 maintains the separation, and thus two distinct hearts are pro- 

 duced. When the head continues to grow, while the cephalic 

 hood is arrested, the former is reversed backwanl, and forms a 

 hernial protuberance in the upper part of the umbilical opening, 

 behind the heart. The slowness of development of the blood 

 globules and vascular area is an obstacle to the formation of the 

 blood, and tends to produce a dropsical condition, a frequent cause 

 of anencephaly. 



Embryos, thus rendered anomalous by the action of relatively 

 low temperatures, — 30° to 34° C, — perish very early, at about 

 the time of the turning of the embryo upon the yolk, and before 

 the appearance of the allantois ; but if, before this period, the eggs 

 be submitted to the normal temperature of incubation, — 10° C., 

 — development may be considerably increased before death, with 

 results very interesting to the embryologist. A very remarkable 

 fact resulting from these experiments is, that embryos submitted 

 to identical physical conditions present great diversity in their 



