No. 1.] ORIGIN OF HUMAN MONSTERS. 23 
of which they used a great variety. In general, they employed 
variations in temperature during incubation and, although 
they produced many kinds of monsters, they never could 
predict which kind they were to obtain from a given batch of 
eggs. It is, therefore, very apparent why experimental tera- 
tologists did not make much headway as long as they experi- 
mented upon the chick. However, they did establish two facts: 
first, that monsters are produced from the hen’s egg by all 
kinds of external influences, as varnishing the shell, placing 
the egg in the vertical position, change of temperature, trau- 
matic means, shaking, magnetic and electrical influences, by 
gases which penetrate the shell and by a great variety of 
chemical poisons and toxines injected into the white of the 
egg. In general, any substance which either interferes with 
the nutrition of the egg or poisons it, causes the embryo to 
become abnormal, but a special kind of monster is never 
produced by a given teratogenic agent. In this respect the 
experiments upon anamniotic eggs are far more satisfactory. 
Panum classified the monsters he produced into two great 
groups: (1) Those in which the whole embryo is involved, 
(2) those in which but part of it is abnormal. Under the 
first group there are (a) flattened forms, that is, the germinal 
area is not much changed in shape; (0) flattened forms with 
the production of red blood, i. ¢., only the embryo is affected ; 
(c) cylindrical forms, the embryo becomes abnormal in a more 
advanced stage; and (d) amorphous forms. This first group, 
with its four subdivisions, may possibly be compared with the 
great variety of irregular monsters of which the lithium larva 
may be considered the type. At any rate, we may say that 
there is an analogy. Certainly there is a similarity between 
the cylindrical forms, which do not live long, and the de- 
formed fishes obtained from Fundulus by means of lithium - 
chloride solutions. The great change which has taken place 
in both varieties makes it impossible for either of them to 
exist for a longer time. A similar form of monster is also 
often found in mammals, and His, in adopting Panum’s ter- 
minology, has classed it with cylindrical monsters. The 
