190 



SCIENCE. 



[Vol. VII., No. 16$ 



confirmation of Mr. Harrison's published account of 

 the finding: of the limestone tablet. If this evidence 

 leads to the conclusion that these relics are modern 

 productions, as I believe it does, there is no necessity 

 for the present of 'further investigation,' — a con- 

 clusion Mr. Mac-Lean seems to have reached while 

 writing his ' Mound-builders.' Cyrus Thomas. 



The claimed wheat and rye hybrid. 



In Science of Jan. 15 appears an article from Dr. 

 Sturtevant, which, to save words, I will call a criti- 

 cism of an account of my rye and wheat hybrids, pub- 

 lished in the Century magazine of last January by 

 Charles Barnard. Mr. Barnard, after an examina- 

 tion of the plants at my place last summer, gives 

 their history, accepting, without question, their 

 hybrid origin. Dr. Sturtevant, who also examined 

 them last summer, begs to dissent. He considers 

 the evidence adduced only 'sufficient to establish 

 grave doubts.' 



While we were on our way to the plots. Dr. Sturte- 

 vant remarked that he wanted me to know that he 

 was ' incredulous as to the whole thing.' While we 

 were returning, he said, l< I am convinced that they 

 are hybrids, but I question whether they will not be 

 found to be distinctly either wheat or rye." In the 

 Science article referred to, he next states that he has 

 compared the pictures of a few of these heads which 

 appeared in the Rural New-Yorker with those of five 

 old varieties which he mentions, and finds them 

 closely alike. Then he remarks that he does not 

 question the ' attempt at a cross.' The ' variability 

 effected is.' he admits, ' indicative of a foreign pollen." 

 This variability, which he believes not to be due to 

 hybridization, the doctor explains by an ' hypothesis.' 

 It is that under the stimulus of the rye pollen, 

 atavism has resulted, whereby varieties dormant in 

 the wheat (female) plant have made their appearance. 

 Finally he expresses the hope that some one, expert 

 in agricultural botany, may 1 investigate a series of 

 these specimens.' 



Dr. Sturtevant, though he states that he has care- 

 fully studied the 1 published claims,' has apparently 

 overlooked the published fact that specimens of these 

 hybrids have been sent to no less than six well- 

 known botanists, several of whom have replied that 

 they were evidently hybrids, while others replied 

 to the effect that the hybridization was a most inter- 

 esting fact, etc. 



Now, if we emasculate the florets of a head of 

 wheat while the anthers are immature, and repeat- 

 edly apply rye pollen, and thus succeed in attaining 

 ten grains, from which, in three years, at least fifty 

 different varieties appear, differing as widely as any 

 known wheats differ from each other, while some of 

 them resemble rye more than wheat, can anyone 

 reasonably doubt that a hybridization was effected I 

 Why assume any thing else whatever ? What does 

 Dr. Sturtevant mean by ascribing such changes to 

 the 1 stimulus of foreign pollen ' as something differ- 

 ent from the sexual effect of foreign pollen ? Sup- 

 pose atavism is shown in some of these : does it not 

 prove, all the same, that hybridization was effected ! 

 A hybrid may show all, some, or none of the 

 characteristics of either parent, and still be a hybrid, 

 as has often been revealed in the later seedling pro- 

 geny. 



In drawing resemblances between the pictures in 

 the Rural New-Yorker an 1 those of which he speaks. 



the doctor, very likely, forgets an important fact ; 

 viz., that in many of the heads of the plants most 

 resembling rye, the spikelets bear but two kernels, 

 while many are wholly abortive. Again : the botani- 

 cal relationship is marked not only by narrower 

 glumes, by fewer florets and grains, but by the fact 

 that the culms beneath the head for an inch or so 

 are hairy, — a characteristic that never occurs on 

 wheat culms. The color of both the culms and leaves 

 is also distinctly lighter (more glaucous) than that of 

 wheat, and the habit of the young plant is that of 

 rye. E. S. Carman. 



A recent ice-storm. 



The trees in central Massachusetts, along the line 

 of the Boston and Albany railroad from Worcester 

 to Spencer, suffered severely from the weight of ice 

 formed upon them during the storm of Feb. 11-13, 

 that caused the recent destructive floods. It was 

 noticeable that the trees which exposed the largest 

 surface for the attachment of ice did not suffer most : 

 the pines with their green needles, and the oaks with 

 their dead leaves, generally escaped injury ; and the 

 slender birches were saved by bending instead of 

 breaking. But from fiv^ to twenty per cent of the 

 other deciduous trees were more or less hurt. The 

 side limbs were not often broken : it was nearly 

 always the vertical top-stems that sustained the most 

 injury, apparently because their natural position was 

 farthest from that into which the weight of the 

 clinging ice forced them. 



Can some of your readers furnish direct observa- 

 tional evidence to show why the pines and leafy oaks 

 escaped, while the bare trees were so much damaged ! 



W. M. Davis. 



Cambridge, Feb. 20. 



Corrections of thermometers for pressure. 



If any of your readers interpreted our reference in 

 Science, Feb. 12, to a letter from the signal office, as 

 your correspondent, Sig., feared they might do, we 

 regret it, and are glad that the import of that letter 

 has been fully explained. We are well aware that 

 many of our text-books on heat refer to the effect of 

 pressure on the thermometer, and state how to pre- 

 vent it in some instances. The effect of appreciable 

 changes of pressure on the thermometer seemed to 

 us to be sufficient to demand correction in all accu- 

 rate thermometric work. If such corrections are 

 generally made, they are omitted in the report of 

 experiments. F. P. Venable. 



J. W. Gore. 



University of North Carolina, Feb. 22. 



Is the dodo an extinct bird ? 



Referring to Dr. Shufeldt's article (Science, vii. l4o) 

 respecting the supposed present existence of the 

 dodo, it may be desirable to state, for the benefit of 

 those who are not already aware of the fact, that the 

 so-called dodo from Samoa, mentioned in the clipping 

 1 from an English newspaper,' is not the dodo at all, 

 but the dodo-pigeon, Didunculus strigirostris, a living 

 specimen of which was last year presented to the 

 national museum by Dr. T. Canisius, ex-consul of the 

 United States at Samoa. This specimen was, at latest 

 account, thriving in the zoological garden at Phila- 

 delphia. Robert Ridgway. 



Smithson. inst., Feb. 15. 



