338 The “ Papille of Retzius” and the Cortex of Embryos 
smoothed out later by the development of the adjacent layers. Shortly 
after this Hochstetter, 98, p. 5, briefly refers to the granulations of the 
pyramidal cell layer described by Retzius. He confirms their presence in 
poorly preserved brains, and designates this appearance as a decomposition 
phenomenon, without giving any further evidence. 
Two years later His, 00, not having noticed the observations of Retzius, 
described independently the same peculiar granular or wart-like character 
of the pyramidal layer in embryo brains of the fourth month; and again 
in his last work His, 04, he describes at some length this appearance 
under the title “ Die Retziusschen Warzchen.” One of his illustrations 
is reproduced in Fig. 1. Though in his discussion he admits that it is 
Gane BIG. 2 
Fie. 1. Section through the occipital lobe of the brain of a human embryo, 
12 cm. long (end of 4th month), showing the irregularities of the pyramidal 
zone caused by the fungiform clumping of the cortical cells, the so-called 
papille of Retzius. Taken from His, o4, Fig. 75. 
Fic. 2. Section from the brain of a human embryo of about the same 
age and taken from the same place as shown in Fig. 1. Here the pyramidal 
zone consists of a compact layer with parallel borders, which, with the excep- 
tion of three transitory fissures presents a perfectly smooth outer surface, 
and shows no trace of the Retzius papille. 
still an open question; yet he is apparently inclined to consider the 
papille as normal, and does not hesitate to discard the possibility referred 
to by Retzius of their being pathological, on the ground that several of 
his specimens, which showed characteristic cortical papille, came from 
healthy individuals who had committed suicide, and the foetuses them- 
selves appeared normal. He also argues that if it were a post-mortem 
alteration, associated with the swelling of the tissues, then the superficial 
layer would also present an irregular surface, which is not the case. 
Neither His nor Retzius accounted for the fact that this phenomenon 
