RECORDS OF MEETINGS OF 1906 275 



ous. In subsequent stages, the elevated cap disappears, the mesoblast 

 sac with its lateral pouches is compressed and the three cavities thus obliter- 

 ated, persist as clefts between the layers of mesoblast. These are com- 

 parable in part to the somatic and splauchnic mesoblast observed in other 

 reptiles. In the horned toad four cell masses are thus to be distinguished, 

 first, one from the roof of the mesoblast sac, second, one from the roof of 

 the two lateral pouches, third, one from the floor of the lateral pouches, 

 fourth, one from the floor of the median mesoblast sac. The last extends 

 but a short distance in front of the ventral opening of the blastopore, in a 

 position lateral to it. 



These facts may be regarded as added evidence that the yolk-cleavage 

 theory of Wenckebach and Weldon is applicable to the reptilian egg. In 

 the egg of the horned toad there is far less interference of yolk and more 

 cellular differentiation, the blastoderm is less compressed because of this 

 and because of the pinching off of the germ from the yolk. The processes 

 attending the formation of the chorda and mesoblast are not obscured by 

 compression as in most other forms. The behavior is much like that in 

 the upper half of a frog's egg. 



Dr. de Ybarra said that the author of this invaluable scientific and histori- 

 cal document was Dr. Diego Alvarez Chanca, of Seville, Spain, who wrote 

 it with his own hands in the form of a letter addressed to the Municipal 

 Council of his native city, and dated at the port of Isabella, in the island of 

 Hispaniola or Santo Domingo, West Indies, at the end of January, 1494. 

 The author was a distinguished practitioner of much learning and profes- 

 sional skill, who held the position of Physician-in-Ordinary to the King and 

 Queen of Castile and Aragon, and had attended their first-born child, 

 Princess Isabella (who afterward became Queen of Portugal) during a seri- 

 ous illness the year before. He was especially appointed by the Spanish 

 monarch to accompany Columbus on his second voyage of discovery to 

 America, came over in the same ship with him, and saved his life, as well 

 as the lives of many high dignitaries and young gentlemen belonging to the 

 Spanish nobility, who were very sick during their stay at the island of His- 

 paniola. 



On his return to Spain, Dr. Chanca published in Spanish, in the year 

 1506, a treatise on the treatment of pleurisy {Para curar el mal de costado), 

 and a few years after, in 1514, a commentatorial work in Latin, criticising 

 the book, entitled " De conservanda juventuie et retardanda senedute," whose 

 author was another distinguished Spanish physician named Dr. Arnaldo 

 de Villanova. The title of the second work of Dr. Chanca is " Commentum 

 novum in parabolis divi Arnaldo de Villanova." 



This historical first document about the flora, the fauna, the ethnology 



