310 



SCIENCE 



[N. S. Vol. XLIX No. 1265 



earliest stages and subsequent transforma- 

 tion." " The equivalence of hematopoietic 

 anlag-es" is, as may be read in the article, 

 a reference to hematopoietic centers. This 

 paper states that the endothelial cell is " a 

 hematopoietic anlage," that is, a source of 

 blood coi-puscles. That it does not give rise 

 to blood-cells (is not such an anlage) is the 

 converse of this proposition, as recently ex- 

 pressed in the British Journal. All organs in 

 young embryos instead of being called hearts, 

 stomachs, etc., may be called anlages of the 

 same, giving abundant opportunity to employ 

 the word, and necessitating references to 

 "early anlages." In numberless cases it is 

 used in place of a more exact term, e. g., 

 anlage of the liver, for hepatic diverticulmn, 

 or is introduced redundantly, as " the evagina- 

 tion which forms (the anlage of) the arm." 

 Its entire absence from many of the most 

 technical and best expressed embryological 

 papers shows clearly that it is not needed. 

 Is the English language enriched by it? It 

 certainly could be employed in general litera- 

 ture: 



Tall oats from little anlages grow, 

 Large streams from little anlages flow. 



The child is anlage of the man; and Lowell 

 might exclaim, Puritanism — the anlage of 

 democracy ! 



But in the interest of scientific accuracy 



and purer English it should be deleted. The 



term, if it remains, will mark the period of 



German dominance in American embryology. 



Frederic T. Lewis 



a simple covering device for the ocular 

 of the microscope 



, To the Editor op Science: I have experi- 

 enced so much trouble and expense from the 

 injury to eye-glasses by contact with the ocular 

 of the microscope, that I venture to describe 

 my experience in solving the problem in the 

 hope that it may be of interest to others simi- 

 larly annoyed. Not being able' tO' use the 

 m.icroscope without the correction to vision af- 

 forded by the eye lenses, I found for a number 

 of years that the harder glass in the ocular 

 invariably — in the course of six months or a 



year — covered the eye lenses with a maze of 

 minute scratches and abrasions, rendering them 

 unfit for further use and necessitating a very 

 considerable expense in the purchase of new 

 lenses, to say nothing of the lowered efficiency 

 of the damaged glasses in the interim. 



I first secured from one of the leading op- 

 tical companies a pair of heavy rubber caps 

 such as are used by them as a dust cap to pro- 

 tect oculars in storage. By cutting away a 

 circular opening in the center of the cap (do 

 not make it too large) I found the rim of rub- 

 ber kept the two sets of lenses from coming in 

 contact. These caps can readily be shifted 

 from one ocular to another as occasion de- 

 mands, or the cost is so slight that several sets 

 can be afforded. They are, however, rather 

 cumbersome and force the eye away from the 

 lens perhaps an eighth of an inch, which is not 

 always satisfactory. 



, A much simpler and, on the whole, more 

 satisfactory device may be made by taking a 

 circular piece of ordinary sheet rubber (such as 

 dentists use extensively) about an inch and a 

 half in diameter; cutting a small hole at the 

 center, and stretching and tying it securely 

 with fine thread below the knurled cap of the 

 ocular. This allows the eye to approach very 

 closely to the ocular; and, besides thoroughly 

 safeguarding the eye-glasses from injury, it 

 does away with the very annoying noise caused 

 by the constant shifting of the two glass lenses 

 on each other. 



I now have every ocular covered in this way 

 and shall never again be without the comfort 

 and economy so afforded. 



Clell Lee Metoalf 

 ■ Department op Zoology and Entomology, 

 Ohio State TJniveesitt 



curious differentiation in frost 



EFFECTS 



To THE Editor of Science : A curious differ- 

 entiation in frost effects on foliage came under 

 the writer's observation yesterday. On Fri- 

 day morning, l^ovember 1, a self-recording 

 standard thermometer registered 32 degrees F. 

 as the minimum during the preceding night, 

 followed by a record of 31 degrees the follow- 



