REVIEW. 
On the so-called Chorda of the Ascidian larve, and the al- 
leged affinity of the invertebrate and vertebrate animals. 
By W. Donirz (‘ Reichert und du Bois Reymond’s Archiv 
fiir Anatomie et Physiologie’). 
Dr. Donitz has availed himself of a stay in Naples to 
study the development from the egg of Clavellina lepadiformis. 
The Berlin zoologist, as a result, comes to the conclusion 
that Kowalewsky and Kupffer have unfortunately made a 
very great mistake in pronouncing the development of Asci- 
dians as broadly and generally identical with the develop- 
ment of the vertebrates. He, on the contrary, has been 
taught by his researches that the development of the Asci- 
dians speaks in a very distinct manner precisely against the 
affinity of the invertebrates and the vertebrates. One 
would think that men like Kowalewsky and Kupffer under- 
stand something of the developmental history of animals, and 
especially of the vertebrates. Dr. Donitz, nevertheless, ad- 
monishes the former especially, that he makes use of such 
expressions as keimblatter, chorda, nervous system, &c., in 
such a way as though a signification, long since firmly estab- 
lished in science, had not been attached thereto. Now, since 
others are included in this crushing condemnation of Kowa- 
lewsky and his work, who have given their adhesion to his 
researches ; and since to these last, such men as Gegenbauer 
and Haeckel belong, not to mention so many others, we 
are naturally in a state of anxiety to know what kind of 
argumentation it is which Dr. Donitz brings into the 
field. 
Fortunately we find at once a capital point discussed, 
namely, the definition of the chorda—that is, of course, the 
signification of this structure, “‘so long since firmly estab- 
lished in science.” It is, according to Dr. Donitz, “an un- 
paired connecting-piece between the two symmetrical halves 
of the vertebral system and is itself a part of the same. The 
existence of the chorda is accordingly conditioned not by its 
histological structure but by its embryological development.” 
