1881.] 



MICEOSCOPICAL JOURNAL. 



23T 



took a special examination of the bottom, 

 and soon discovered facts which led me to 

 think I was at last on the true scent. The 

 mud when first filtered from the water 

 has no odor, nor has the water which 

 comes from it, and which, as the analyses 

 show, contains a large amount of nitro- 

 genous matter. This water, further, has 

 not a trace of the " cucumber taste." The 

 question at once suggested itself : Does 

 this taste come from something situated 

 on some other part of the bottom, or may 

 it be developed by contact of the mud and 

 bottom water with air ? A thin layer was 

 spread on ordinary filtering paper and 

 allowed to lie for a time. In about half an 

 hour an odor was emitted from this ma- 

 terial, whereas, at first, as has already been 

 stated, it had no odor whatever. The 

 odor increased for a time, but afterward, 

 in the course of about an hour, the odor 

 disappeared entirely and did not reappear. 

 The odor suggested somewhat that with 

 which we are all familiar, but I could not 

 positively identify the two. There is, then, 

 evidently something in the bottom, and 

 which, by contact with air, is capable of 

 giving off an odor. An examination soon 

 revealed the presence of green masses, 

 varying in size from that of a pin-head to 

 that of a pea. These were present in a 

 considerable quantity, and, in allowing the 

 vessels which contained the mud to stand 

 quietly for a short time, the green masses 

 rose to the surface of the mud. 



At this point I consulted Prof. W. G. 

 Farlow, of Harvard College, for the pur- 

 pose of procuring an authoritative state- 

 ment concerning the nature of this green 

 substance. He at once identified the ma- 

 terial as plants belonging to the Nostoc 

 family. The Nostocs are known to give 

 off a disagreeable odor when decaying, 

 and they have been observed in a number 

 of other cases of contaminated waters. I 

 at once picked out some of the Nostocs, 

 and exposed them to the air, expecting to 

 get a much stronger odor than I had ob- 

 tained from the mud ; but, to my surprise, 

 the odor did not appear at all readily, and 

 did not suggest the cucumber odor ; nor 

 did it become at any time nearly as strong 

 as that of the mud itself, exposed under 

 exactly the same conditions. After exam- 

 ining the subject carefully, I feel confi- 

 dence in stating that, whatever may be the 

 properties of the nostocs found at the bot- 

 tom of Farm Pond, these plants are not 

 the cause of the '• cucumber taste." They 

 may possibly contribute something to the 

 taste ; though, in view of other observa- 



tions made by Prof. Farlow, I think this 

 improbable. Certainly they are not the 

 prime cause. 



This conclusion agrees with the 

 statement of Prof. Farlow, already 

 referred to on page 15 of the current 

 volume of this Journal, and it is of 

 considerable importance ; showing 

 that the pig-pen odor and the cucum- 

 ber taste originate in totally different 

 causes. 



Finally, an examination of the de- 

 bris, collected on a screen at one of 

 the effluent gates, led to the discov- 

 ery of what is doubtless the cause of 

 the cucumber taste — the decomposi- 

 tion of a fresh-water sponge. Once 

 more quoting the report : — 



I collected a considerable quantity of 

 the substance and convinced myself that 

 each piece picked up had this strong odor, 

 and, further, that pieces of it were con- 

 stantly being stopped by the screen. The 

 other materials picked off the screen did 

 not have any odor that was in the least 

 striking. There is not the slightest doubt 

 that this peculiar substance is the only 

 thing thus far found in- the pond which 

 has an odor unquestionably like that of the 

 " cucumber water," and this substance 

 must be present in considerable quantity, 

 or it would not have been found to the ex- 

 tent described above. Prof. Farlow, to 

 whom I submitted it first, pronounced it 

 to be a fresh-water sponge. Acting on 

 this information, I at once took my speci- 

 mens to Prof. Alpheus Hyatt, a recognized 

 authority of the highest standing on the 

 subject of sponges, as well as other sub- 

 jects. He kindly examined them, and 

 pronounced them to be sponges. He, too, 

 was struck by the odor, and recognized 

 the strong similarity between this odor 

 and that of the " cucumber water." His 

 remarks on the subject are herewith 

 submitted : 



[Copy.] 



The specimen is that known as Spon- 

 gilla fitiviatilis. This sponge is common 

 in all fresh-water ponds, and in certain 

 places is very abundant. While living it 

 has a very strong odor, which is increased 

 by decomposition. Masses of it easily de- 

 compose, and are often found partly liv- 

 ing and partly decayed. It occurs on 

 muddy bottoms ; and also grows on sticks 

 and other hard substances. The odor of 



