146 



THE AMERICAN MONTHLY 



August, 



the lungs are among the most active 

 and important of his organs. All 

 the blood in the body passes through 

 them in the course of a very few 

 minutes to be aerated. The vessel 

 which carries the blood to these 

 organs is called the pulmonary ar- 

 tery. Before birth, however, the 

 blood is aerated by another organ, 

 and the lungs have scarcely any 

 function. They, of course, can re- 

 ceive no air and lie as collapsed,8olid 

 bodies in the cavity of the chest. 

 The blood which after birth is car- 

 ried to them in such volumes is, at 

 this time, in great part taken to 

 other parts of the body by a branch 

 which is, after birth, closed. The 

 lungs receive abundant nutrition 

 from another set of vessels, the 

 bronchial arteries, which are deri- 

 ved from the aorta. At this period 

 of life very little blood is conveyed 

 to the lungs by the pulmonary ar- 

 tery, which is afterwards called 

 upon so suddenly to convey such 

 volumes of blood. As to the con- 

 dition of this vessel before birth, I 

 have never seen anything printed. 



T have happened upon some ob- 

 servations which throw light upon 

 this subject. 



Some years ago, I made an injec- 

 tion of the blood-vessels of the lung 

 through the pulmonary artery of a 

 new-born child, that had never 

 breathed. I cut the injected lung 

 into sections, and examined great 

 numbers of them in connection 

 with Professor H. A. Johnson, 

 of this city. 



While making these examinations 

 we came upon appearances which, 

 at first, puzzled us. The structures 

 in question were sometimes round 

 and sometimes in longer or shorter 

 ovals. The outer portion consisted 

 of several concentric layers inter- 

 spersed with bright, oblong nuclei. 

 Within was an irregular star-shaped 

 apperance, of a blue color from the 



prussian-blue injecting material. 

 Very soon the interpretation dawn- 

 ed upon us. What we saw was the 

 undistended pulmonary artery. The 

 vessel during foetal life receives a 

 large quantity of nutriment from 

 the bronchial arteries. Its walls 

 grow to the full thickness they are 

 to be after birth, but there has been 

 no force to stretch them out to their 

 subsequent diameter. 



The force of the injection had 

 been sufficient to drive the fluid 

 through the vessel, but not to dis- 

 tend it. 



The fact might be inferred almost 

 without observation and this, per- 

 haps, is the reason that it has not 

 been described. 



Soon after the observations were 

 made, specimens were exhibited at 

 a meeting of the State Microsco- 

 pical Society of Illinois. A brief 

 description was printed at that time 

 in the Transactions of the Society, 

 which were published in the Lens. 



The above facts seem to be of 

 some practical importance in a 

 medico-legal point of view, as the 

 contracted condition of the vessel 

 indicates with certainty that the full 

 volume of the blood has not been 

 sent to the lungs, and consequently 

 that the child has never breathed. 



Directions For Cleaning 

 Diatoms. 



{Continued froin page 110.) 



It should have been remarked in 

 the former paper, that although 

 distilled water is not necessary, ex- 

 cept for the final washings, filtered 

 water must be employed through- 

 out, otherwise it will often happen 

 that after the diatoms are cleaned, 

 a glance through the microscope 

 will reveal filaments of algee from 

 the water, or, what is a far more 

 serious matter, diatoms which do 

 not belong to th# gathering may be 



