July 21, 1922] 



SCIENCE 



77 



ers. What psychologist has not experienced 

 some form of emotion when he has envisaged 

 the pile of trash and supertrash accumulated 

 behind the drawers at the periodical laboratory 

 housecleaning festivity! The affective experi- 

 ence of the conscientious director of the labora- 

 tory is further embellished by the knowledge 

 that this trash is expensive to replace and 

 wasteful of energy and time spent in reorgan- 

 izing the contents of the cabinet. 



In an earlier attempt to prevent mutilation 

 of papers in this wise a cardboard of medium 

 weight was placed in each drawer on top of 

 the papers. Instructions printed in bold char- 

 acters advised students and others to replace it 

 before closing the drawer. But since failure 

 to heed the advice did not entail consequences 

 similar to the infraction of a natural law, treat- 

 ment of the situation by suggestion was un- 

 successful. The next step was to tack a piece 

 of cardboard over the back of the drawer and 

 reaching forward about eight or ten inches. 

 While this device proved to be a great help, 

 it did not prevent catching and rolling back 

 at the front of the drawer when it was pulled 

 out. 



The best solution of the difficulty seems to 

 lie in a very simple arrangement which if em- 

 bodied in the original construction of a cabinet 

 ought to be less expensive than a case of draw- 

 ers, but it can also be installed where drawers 

 are already in use. In the simpler plan the 

 drawers are slides that fit into grooves at the 

 side of the cabinet and are made with strips 

 1% inches high at the front and a trifle lower 

 at the back, but affording ample room for the 

 standard-sized sheets. On each slide a heavy 

 cardboard cover is hinged at the back with 

 heavy binder's cloth over the top of the strip 

 and is cut large enough to fall just within the 

 front strip or face of the slide. A leather 

 "pull" or flap by means of which the cover can 

 be readily lifted is fastened to it near the 

 front. The apparent inconvenience of having 

 to pull the drawer almost entirely out before 

 the cover can be sufficiently lifted to extract 

 the papers is more of an advantage than a 

 hindrance in view of the well-known fact that 

 most of the untidiness of cabinets is due to the 

 careless extraction and introduction of papers 



with drawers insufficiently opened. Papers 

 that lie beneath are thereby frequently pulled 

 or pushed back and crumpled up. If the cab- 

 inet were constructed so that the grooves at 

 the sides extended six inches or more, or in 

 other words if the sides of the cabinet were 

 built six or more inches wider than the depth 

 of the slides, the slides could be held in place 

 while the covers were lifted and the papers 

 handled, provided that the remaining slides 

 were always systematically returned to their 

 full extent. 



A neat and carefully arranged "color cab- 

 inet" is always an asset to the well-appointed 

 laboratory and there seems to be no reason why 

 we should not begin at this point to inculcate 

 the ideals of order and system in the minds of 

 our young scientists and at the same time to 

 increase the efficiency of the laboratory accord- 

 ing to those standards for which the newer 

 generation is so valiantly fighting! 



Christian A. Ruckmick 

 Wellesley College 



THE HUMAN YOLK SAC 



Some time ago there came under my ob- 

 servation two specimens of early hmnan twins, 

 both of which showed a direct developmental 

 relation to single yolk sacs. For record I pub- 

 lished a brief note^ announcing the discovery 

 of this important condition and emphasizing 

 the single-ovum origin which it implies; in 

 addition were appended several deductions or 

 speculations of secondary importance. In a 

 recent issue= of this journal Professor ¥. T. 

 Lewis has raised certain objections which de- 

 mand consideration that the intent of my 

 former condensed account be not misunder- 

 stood. 



The second specimen described in that pub- 

 lication had a single yolk sac and yolk stalk 

 connected to one embryo of the twin pah-; the 

 other embryo lacked both stalk and sac. Pro- 

 fessor Lewis believes this indicates the early 

 obliteration of one of the originally paii-ed 

 stalks. My interpretation was that an early un- 

 equal division of the embryonic mass had left 



1 Anatomical Record, Vol. 23, pp. 245-251. 

 - Science, Yol. 55, p. 478. 



