452 



SCIENCE. 



LVol. IV., No. 93. 



of the audience can follow him. Let him 

 alwajs remember that there are some state- 

 ments which the mind cannot readily receive 

 through the portal of the ear ; and there are 

 but few which cannot be simultaneously pre- 

 sented, both to the eye and the ear. The dia- 

 gram, the printed formula, the abstract, may 

 cost the speaker a little expenditure ; but it 

 will save the hearer a vexatious outlay of time 

 and attention. Third, Let there be a liberal 

 margin allowed for social intercourse outside 

 of the meetings, not merely for public recep- 

 tions and excursions, but for those informal 

 introductions and interviews which to many 

 persons are the best part of scientific gather- 

 ings. We should not then hear it said so 

 often, "This would have been a very pleasant 

 meeting were it not for the papers which were 

 read." 



by a child who had been fitted for taking them 

 up by the right kind of preparation. The 

 argument is a novel one, and it certainty seems 

 plausible. 



A remark made in one of the papers read 

 before the recent Woman's congress in Balti- 

 more suggests an interesting argument in favor 

 of the kindergarten. It is well known, that, 

 in its development, each new-born being passes 

 through very much the same stages that his 

 ancestors have been through before him. Even 

 after birth, the growth of the child's intelli- 

 gence simulates the progress of the human 

 race from the savage condition to that of civi- 

 lization. It has been shown by Prayer, and 

 others who have studied infant-development, 

 that a faculty which has been acquired by 

 the race at a late stage is late in making 

 its appearance in the child. Now, reading 

 and writing are arts of comparatively recent 

 achievement. Savage man could reap and 

 sow and weave, and build houses, long before 

 he could communicate his thoughts to a person 

 at a distance by means of written speech. 

 There is, then, reason to believe that a child's 

 general intelligence would be best trained by 

 making him skilful in many kinds of manual 

 labor before beginning to torture him with 

 letters ; and the moral to be derived is, that 

 primary instruction should be instruction in 

 manual dexterity, and that reading and writing 

 could be learned with pleasure and with ease 



LETTERS TO THE EDITOR. 



Change in the color of the eye. 



In Science, p. 367, you say the color of the iris, 

 ' after early childhood ' ' does not vary with age:' I 

 think I can give you positive evidence that it does. 

 My own eyes were called black (in reality dark brown) 

 until after I was forty years old. About that time 

 they commenced to change, and are now blue-gray, 

 with streaks of light hazel, which last are fast fading 

 out. The same thing happened with my father's eyes. 

 I remember him at forty years and under, with 

 thoroughly black eyes, and there are portraits of him 

 which show him thus; but between forty and fifty, 

 his eyes changed, and eventually became a blue, with 

 a very slight tint of hazel, not noticeable without 

 close observation. Theodore F. McCurdy. 



Norwich Town, Conn. 



The eggs of Ornithorhynchus. 



The editorial comments in a recent number of 

 Science (p. 412), on the revival of forgotten statements, 

 lead me to believe that some more old matter may be 

 revived with profit. The telegram sent to the meet- 

 ing of the British association from Professor Liver- 

 sedge, announcing the fact ascertained by Mr. W. H. 

 Caldwell (Science, iv. 261 ), that Ornithorhynchus lays 

 eggs, has been universally hailed as an entirely new 

 discovery; and a number of the prominent British 

 zoologists, whom we had the pleasure of welcoming to 

 Washington recently, were unaware that the ovipari- 

 ty of the monotreme had long before been definitely 

 announced, and an egg figured. Nevertheless, such 

 is the fact; and an extensive series of old comments 

 and applications of the fact appears in the literature 

 of zoology. I need only refer to some of the most 

 prominent, and others can follow up the subject in the 

 publications of the day. 



In 1829 G-c offroy Saint-Hilaire published a memoir 

 in the Annates des sciences naturelles (xviii. 157-164), 

 in which he reproduced a figure of an egg of the natu- 

 ral size (pi. 3, fig. 4). This was communicated to him 

 by Prof. Eobert E. Grant of London, who drew one 

 of a nest of four obtained by a Mr. Holmes. Two of 

 these eggs were reported to have been obtained by the 

 ' Museum de Manchester; ' and it would be well for 

 our Manchester friends to hunt them up, and see 

 whether they are still to be found. As a result of a 

 general belief in the oviparity of the animal, several 

 of the naturalists of the day revised the classification 

 of the vertebrates. 



In 1830 Dr. Joh. Wagler, in his ' Naturliches 

 system der amphibien,' proposed a peculiar class 

 (Gryphi — Greife), in which, however, by illegitimate 

 assumptions, he included the ichthyosaurians, plesi- 

 osaurians, and pterodactyles. 



In 1831 Charles L. Bonaparte, prince of Musigna- 

 no, in his ' Saggio di una distribuzione metodica 

 degli animali vertebrati,' also isolated the mono- 

 tremes as a peculiar class (Monotrema), defining it 

 in the following terms: "I Monotremi sono animali 

 vertebrati, a sangue calido, ovipari, quadrupedi; respi- 

 rano per mezzo di polmoni ; hanno un cuore bilocu- 

 lare biaurito." 



And even long before the egg was thus figured, 



