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NOTKWORTHY PlIANEltOI '. AMS OF INDIANA. I>V StaNI.KY C'ori.ri'.i;. 



Methods of iNFiLXRATiNci and Staining ix toto the Heads of Veknonia. 

 By E. H. IIeacock. 



In l)C'giiiiun<,' a study of \hv develoiiinent ni the cmliryn sac of WiiKniia. iwo 

 (litHciiltics at onve j>rost'iit tlietiiselves. Tlic first is to iiropi rly stain tlir lu'ad in 

 toll), and the swond to infiltrate witli pai'atfini' so as to lif ahk' to section i)ro|icrly. 



Tiu' forii) is an ordinary coniiiosite. liaxinu twenty or more IIow^ms in each 

 head. The ovary is siii-ronnded i)y a tiiick. solid integument se\i'ral layers of 

 cells deep, and the diflieulty lies in penelrating this coat. 



Before staining or infiltrating, all parts of tiie head al)ove the achenes were 

 eut off, thus securing a smaller body and a more ready penetration. Heads dehy- 

 drated by 96 i>ei' cent, alcohol were wasiied out in distilled water, tiie water i)eing 

 frecjuently changed, until they sank to the bottom of the vial. Tiiey were then 

 stained for seventy-two itours in alum cochineal (( zoker's Formulae). Whei. sec- 

 tioned they sliowed hut a faint trace of stain. Heads dcdiydrated Iiy abs<dute 

 alcohol and stained for seventy-tw() hours in borax carmine, Kleinberg's and 

 Delatield's ha-niato.vylins gave no lietter restilts. 



Heads which had l)een dehydrated l)y absoltite alcohol, washed out in dis- 

 lilled water and stained for seven days in alum cochineal (Czoker's Fcu-muhe) 

 gave gf)od results. The general tone of the stain is dim, but under high power 

 the differentiation is very tine. Heads dehydratnl liy abs<diite ah-olud and 

 stained for seven days in liorax carmine gave very fair results. Tliese results 

 ])oinI to the fact that with long time treatnient the iieads maybe siu'cessfully 

 .staine<l. 



The secoiul dilliculty : iutiltraling with i)aralliue. Tiie lirst me<licum used 

 was iuri)entini'. Heads dehydrated by !l6 per cent, alcoiiol were placetl in tur- 

 pentine for twenty-four hours, then into a mixture of one-lialf turpentine and 

 one-lialf paraHine for twenty-four hours. liieucc into jjiire parafiine (48° C. ) for 

 twentv-four to forty-eight hours. On sectioning the sections were found to tear 

 uut in the center, thus jtroving that [)aratiine had not reached the centej' of the 

 head. Heads dehydrated by al)solute alcohol weri' given the same tieatuienl. In 

 tliis series the sniall heads showed an iiiipro\-cm(.>ul, but still the normal sized 

 heads were not j)roi)erly infiltrated. 



The next medium used was a mixture consisting of one-halt cedar oil and one- 

 half xvhd. Heads dehydrated by alisolute alcohol were placed in this luediuin 

 for twentv-four Iuuh's, then into a mixture of one-half the mc'dinm anil one-ludf 



